Final California 2024 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name: Walnut Creek
Water Body ID: CAR2073104019990218110904
Water Body Type: River & Stream
 
DECISION ID
142494
Region 2     
Walnut Creek
 
Pollutant: Diazinon
Final Listing Decision: Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status Revised
Sources: A Source Unknown | Other Urban Runoff | Surface Runoff
TMDL Name: San Francisco Bay Urban Creeks Diazinon
TMDL Project Code: 9
Date TMDL Approved by USEPA: 05/21/2007
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and 4.1 of the Listing Policy. Under 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status.

Five lines of evidence are available in the administrative record to assess this pollutant.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. A product ban for urban uses of diazinon in 1999 which has caused dramatic reduction in use.
4. Zero of zero recent samples (since the ban) exceeded the evaluation guideline.
5. However, there are not a sufficient number of samples to de-list this waterbody according to Table 4.1 of the Listing Policy.
6. The Pesticides in Urban Creeks TMDL was approved by USEPA on 5/21/2007.
7. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142494, Diazinon
Region 2     
Walnut Creek
 
LOE ID: 93530
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Diazinon.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al. (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142494, Diazinon
Region 2     
Walnut Creek
 
LOE ID: 93531
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Diazinon.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al. (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142494, Diazinon
Region 2     
Walnut Creek
 
LOE ID: 1833
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: Placeholder reference 2006 303(d)
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion:
Objective/Criterion Reference:
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation:
Temporal Representation:
Environmental Conditions:
QAPP Information: QA Info Missing
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 142494, Diazinon
Region 2     
Walnut Creek
 
LOE ID: 272380
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for Diazinon .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al., (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2013-06-25
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142494, Diazinon
Region 2     
Walnut Creek
 
LOE ID: 272442
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for Diazinon .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for diazinon is the median lethal concentration (LC50) of 11 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 11 ug/g is the geometric mean of LC50 values for diazinon from Ding et al., (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2013-06-25
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142506
Region 2     
Walnut Creek
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142506, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 2     
Walnut Creek
 
LOE ID: 283509
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dichlorophenoxyacetic acid, 2,4- (2,4-D) is the USEPA Aquatic Life Benchmark of 299.2 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142506, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 2     
Walnut Creek
 
LOE ID: 283529
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dichlorophenoxyacetic acid, 2,4- (2,4-D) is the USEPA Aquatic Life Benchmark of 299.2 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142506, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 2     
Walnut Creek
 
LOE ID: 283457
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dichlorophenoxyacetic acid, 2,4- (2,4-D) is the USEPA Aquatic Life Benchmark of 299.2 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142506, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 2     
Walnut Creek
 
LOE ID: 283510
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dichlorophenoxyacetic acid, 2,4- (2,4-D) is the USEPA Aquatic Life Benchmark of 299.2 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142522
Region 2     
Walnut Creek
 
Pollutant: 2-Methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142522, 2-Methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid
Region 2     
Walnut Creek
 
LOE ID: 284163
 
Pollutant: 2-Methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for MCPA.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for 2-methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid is the USEPA Aquatic Life Benchmark of 20 ug/L for a vascular plant (acute) for MCPA EHE.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142522, 2-Methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid
Region 2     
Walnut Creek
 
LOE ID: 284144
 
Pollutant: 2-Methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for MCPA.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for 2-methyl-4-chlorophenoxyacetic acid (MCPA):acetic acid is the USEPA Aquatic Life Benchmark of 20 ug/L for a vascular plant (acute) for MCPA EHE.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142529
Region 2     
Walnut Creek
 
Pollutant: Alkalinity as CaCO3
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142529, Alkalinity as CaCO3
Region 2     
Walnut Creek
 
LOE ID: 276610
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142529, Alkalinity as CaCO3
Region 2     
Walnut Creek
 
LOE ID: 276609
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142529, Alkalinity as CaCO3
Region 2     
Walnut Creek
 
LOE ID: 276592
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142529, Alkalinity as CaCO3
Region 2     
Walnut Creek
 
LOE ID: 276593
 
Pollutant: Alkalinity as CaCO3
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
 
DECISION ID
151043
Region 2     
Walnut Creek
 
Pollutant: Ammonia
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

24 lines of evidence are available in the administrative record to assess this pollutant. 2 of the 6 samples exceed the evaluation guideline.

Although there are sufficient exceedances to list for ammonia in this waterbody, the data is not temporally representative of ammonia conditions in the waterbody as required by LP 6.1.5.3. There are only two exceedances for un-ionized ammonia for this decision. Each exceedance is from one site at one day in a year. The listing objective for un-ionized ammonia is calculated as an annual median per site, therefore one sample is insufficient to calculate an annual median to represent two or more seasons. There are no exceedances for total ammonia, which is calculated by a monthly average. Two exceedances are required for a listing, thus at this time there is insufficient data to list for ammonia.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277663
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277646
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 278472
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279439
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279632
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 278888
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279564
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279563
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279442
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279438
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279078
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279291
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279212
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279441
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 279338
 
Pollutant: Ammonia (Unionized)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Ammonia as N, Unionized.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.20 Un-Ionized Ammonia: The discharge of wastes shall not cause receiving waters to contain concentrations of un-ionized ammonia in excess 0.025 mg/l (as N), expressed as an annual median.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277557
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277503
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 278297
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277519
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277850
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277825
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277520
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277556
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 151043, Ammonia
Region 2     
Walnut Creek
 
LOE ID: 277549
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
 
DECISION ID
142480
Region 2     
Walnut Creek
 
Pollutant: Anthracene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142480, Anthracene
Region 2     
Walnut Creek
 
LOE ID: 269588
 
Pollutant: Anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Anthracene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for anthracene is the probable effect concentration (PEC) of 845 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142480, Anthracene
Region 2     
Walnut Creek
 
LOE ID: 269574
 
Pollutant: Anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Anthracene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for anthracene is the probable effect concentration (PEC) of 845 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142480, Anthracene
Region 2     
Walnut Creek
 
LOE ID: 93467
 
Pollutant: Anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Anthracene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for anthracene is 845 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142480, Anthracene
Region 2     
Walnut Creek
 
LOE ID: 93468
 
Pollutant: Anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Anthracene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for anthracene is 845 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142483
Region 2     
Walnut Creek
 
Pollutant: Arsenic
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142483, Arsenic
Region 2     
Walnut Creek
 
LOE ID: 269498
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Arsenic .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for arsenic is the probable effect concentration (PEC) of 33 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142483, Arsenic
Region 2     
Walnut Creek
 
LOE ID: 269622
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Arsenic .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for arsenic is the probable effect concentration (PEC) of 33 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142483, Arsenic
Region 2     
Walnut Creek
 
LOE ID: 93469
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Arsenic.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142483, Arsenic
Region 2     
Walnut Creek
 
LOE ID: 93470
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Arsenic.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142544
Region 2     
Walnut Creek
 
Pollutant: Azoxystrobin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142544, Azoxystrobin
Region 2     
Walnut Creek
 
LOE ID: 280509
 
Pollutant: Azoxystrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Azoxystrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Azoxystrobin is the USEPA Aquatic Life Benchmark of 44 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142544, Azoxystrobin
Region 2     
Walnut Creek
 
LOE ID: 280463
 
Pollutant: Azoxystrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Azoxystrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Azoxystrobin is the USEPA Aquatic Life Benchmark of 44 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142545
Region 2     
Walnut Creek
 
Pollutant: Bensulide
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142545, Bensulide
Region 2     
Walnut Creek
 
LOE ID: 280549
 
Pollutant: Bensulide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Bensulide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Bensulide is the USEPA Aquatic Life Benchmark of 11 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142545, Bensulide
Region 2     
Walnut Creek
 
LOE ID: 280531
 
Pollutant: Bensulide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Bensulide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Bensulide is the USEPA Aquatic Life Benchmark of 11 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
154165
Region 2     
Walnut Creek
 
Pollutant: Benthic Community Effects
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Benthic community effects are being considered for placement on the CWA section 303(d) List under section 3.9 of the Listing Policy. Under section 3.9, when data show benthic community degradation and there is at least one pollutant impairment that could impact benthic macroinvertebrates, the waterbody is placed on the 303(d) List for benthic community effects.

Five lines of evidence evaluating benthic macroinvertebrate bioassessment data are available in the administrative record to assess this indicator. Five of five benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold of 0.79. At least one line of evidence includes sufficient pollutant exceedances to indicate the waterbody is impaired for at least one pollutant. However, there is insufficient data and/or information to determine if at least one pollutant could be impacting benthic macroinvertebrates.

Based on the readily available data and information, the evidence indicates that there is sufficient justification against placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. Although there is insufficient data and/or information to make a beneficial use support determination, the exceedances of the benthic macroinvertebrate samples indicate beneficial uses may be potentially threatened.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Five of five benthic macroinvertebrate bioassessment samples had CSCI scores below 0.79.
4. At least one line of evidence includes sufficient pollutant exceedances to indicate the waterbody is impaired for at least one pollutant related to aquatic life; however, data and/or information are insufficient to determine if the pollutant(s) is impacting benthic macroinvertebrates.
5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 306354
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 207R01271 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.428042 to 0.428042.
Data Reference: California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. 
Guideline Reference: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: Samples were collected from station 207R01271.
Temporal Representation: Samples were collected from 5/11/2016 to 5/11/2016.
Environmental Conditions:
QAPP Information: Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 270339
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Bifenthrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin (Amweg et al., 2005 and Amweg and Weston, 2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 306355
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 207R01591 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.439 to 0.439.
Data Reference: California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. 
Guideline Reference: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: Samples were collected from station 207R01591.
Temporal Representation: Samples were collected from 5/17/2017 to 5/17/2017.
Environmental Conditions:
QAPP Information: Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 287762
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 275949
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Pyrethroids .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Guideline Reference: Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids
Guideline Reference: Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 287601
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 269091
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 93611
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: One sample was collected to evaluate sediment toxicity. The sample exhibited significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 2 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. . For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.
Guideline Reference: Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064
 
Spatial Representation: The sample was collected at station 207WAL020.
Temporal Representation: The sample was collected in June 2008.
Environmental Conditions:
QAPP Information: All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 306351
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 207CE0550 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.54031915 to 0.54031915.
Data Reference: California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. 
Guideline Reference: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: Samples were collected from station 207CE0550.
Temporal Representation: Samples were collected from 7/26/2004 to 7/26/2004.
Environmental Conditions:
QAPP Information: Data were collected using Surface Water Ambient Monitoring Program protocols
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 306352
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 207R00247 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.525871 to 0.525871.
Data Reference: California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. 
Guideline Reference: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: Samples were collected from station 207R00247.
Temporal Representation: Samples were collected from 5/22/2012 to 5/22/2012.
Environmental Conditions:
QAPP Information: Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 306353
 
Pollutant: Benthic-Macroinvertebrate Bioassessments
LOE Subgroup: Population/Community Degradation
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: Benthic macroinvertebrate surveys
Data Used to Assess Water Quality: Water Board staff assessed data for 207R00567 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the threshold. CSCI scores were from 0.388766 to 0.388766.
Data Reference: California Stream Condition Index (CSCI) Scores for the 2024 Integrated Report for Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rehn, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use. 
Guideline Reference: Bioassessment in complex environments: designing an index for consistent meaning in different settings
 
Spatial Representation: Samples were collected from station 207R00567.
Temporal Representation: Samples were collected from 4/30/2013 to 4/30/2013.
Environmental Conditions:
QAPP Information: Data were collected according to BASMAA Regional Monitoring Coalition sampling protocols.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 154165, Benthic Community Effects
Region 2     
Walnut Creek
 
LOE ID: 280624
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Bifenthrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142485
Region 2     
Walnut Creek
 
Pollutant: Benzo(a)anthracene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142485, Benzo(a)anthracene
Region 2     
Walnut Creek
 
LOE ID: 93480
 
Pollutant: Benzo(a)anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Benzo(a)anthracene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for Benzo(a)anthracene is 1050 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142485, Benzo(a)anthracene
Region 2     
Walnut Creek
 
LOE ID: 269831
 
Pollutant: Benzo(a)anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Benz(a)anthracene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for benz[a]anthrazene is the probable effect concentration (PEC) of 1050 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142485, Benzo(a)anthracene
Region 2     
Walnut Creek
 
LOE ID: 93479
 
Pollutant: Benzo(a)anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Benzo(a)anthracene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for Benzo(a)anthracene is 1050 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142485, Benzo(a)anthracene
Region 2     
Walnut Creek
 
LOE ID: 269945
 
Pollutant: Benzo(a)anthracene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Benz(a)anthracene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for benz[a]anthrazene is the probable effect concentration (PEC) of 1050 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142484
Region 2     
Walnut Creek
 
Pollutant: Benzo(a)pyrene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142484, Benzo(a)pyrene
Region 2     
Walnut Creek
 
LOE ID: 270248
 
Pollutant: Benzo(a)pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Benzo(a)pyrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for benzo[a]pyrene is the probable effect concentration (PEC) of 1450 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142484, Benzo(a)pyrene
Region 2     
Walnut Creek
 
LOE ID: 269836
 
Pollutant: Benzo(a)pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Benzo(a)pyrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for benzo[a]pyrene is the probable effect concentration (PEC) of 1450 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142484, Benzo(a)pyrene
Region 2     
Walnut Creek
 
LOE ID: 93482
 
Pollutant: Benzo(a)pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Benzo(a)pyrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Benzo(a)Pyrene is 1450 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142484, Benzo(a)pyrene
Region 2     
Walnut Creek
 
LOE ID: 93481
 
Pollutant: Benzo(a)pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Benzo(a)pyrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Benzo(a)Pyrene is 1450 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142519
Region 2     
Walnut Creek
 
Pollutant: Bromacil
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142519, Bromacil
Region 2     
Walnut Creek
 
LOE ID: 280493
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Bromacil.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bromacil is the USEPA Aquatic Life Benchmark of 6.8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142519, Bromacil
Region 2     
Walnut Creek
 
LOE ID: 280472
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Bromacil.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bromacil is the USEPA Aquatic Life Benchmark of 6.8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142486
Region 2     
Walnut Creek
 
Pollutant: Cadmium
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142486, Cadmium
Region 2     
Walnut Creek
 
LOE ID: 270705
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Cadmium .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cadmium is the probable effect concentration (PEC) of 4.98 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142486, Cadmium
Region 2     
Walnut Creek
 
LOE ID: 270563
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Cadmium .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cadmium is the probable effect concentration (PEC) of 4.98 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142486, Cadmium
Region 2     
Walnut Creek
 
LOE ID: 93493
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cadmium.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142486, Cadmium
Region 2     
Walnut Creek
 
LOE ID: 93494
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cadmium.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142487
Region 2     
Walnut Creek
 
Pollutant: Carbaryl
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142487, Carbaryl
Region 2     
Walnut Creek
 
LOE ID: 280711
 
Pollutant: Carbaryl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Carbaryl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended carbaryl criterion for the protection of aquatic life in freshwater is 2.1 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142487, Carbaryl
Region 2     
Walnut Creek
 
LOE ID: 280729
 
Pollutant: Carbaryl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Carbaryl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended carbaryl criterion for the protection of aquatic life in freshwater is 2.1 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142541
Region 2     
Walnut Creek
 
Pollutant: Chlorantraniliprole
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142541, Chlorantraniliprole
Region 2     
Walnut Creek
 
LOE ID: 280747
 
Pollutant: Chlorantraniliprole
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Chlorantraniliprole.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorantraniliprole is the USEPA Aquatic Life Benchmark of 3.02 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142541, Chlorantraniliprole
Region 2     
Walnut Creek
 
LOE ID: 280767
 
Pollutant: Chlorantraniliprole
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Chlorantraniliprole.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorantraniliprole is the USEPA Aquatic Life Benchmark of 3.02 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142488
Region 2     
Walnut Creek
 
Pollutant: Chlordane
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142488, Chlordane
Region 2     
Walnut Creek
 
LOE ID: 270826
 
Pollutant: Chlordane
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Chlordane .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlordane is the probable effect concentration (PEC) of 17.6 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142488, Chlordane
Region 2     
Walnut Creek
 
LOE ID: 270885
 
Pollutant: Chlordane
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Chlordane .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlordane is the probable effect concentration (PEC) of 17.6 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142488, Chlordane
Region 2     
Walnut Creek
 
LOE ID: 90709
 
Pollutant: Chlordane
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Zero of 1 samples collected exceeded the criteria for chlordane concentration (Sum of trans-Chlordane, cis-Chlordane, cis-Nonachlor, trans-Nonachlor, and Oxychlordane).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Waters shall not contain substances in concentrations that result in the deposition of material that causes nuisance or adversely affects beneficial uses. (Water Quality Control Plan for the San Francisco Bay Basin).
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: The Probable Effect Concentration for Chlordane in freshwater sediments is 17.6 ug/kg(MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected at the following station 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected on 6/17/2008.
Environmental Conditions:
QAPP Information: The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142489
Region 2     
Walnut Creek
 
Pollutant: Chloride
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281425
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281737
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281881
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281605
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281593
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281714
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281406
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281721
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281591
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281865
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281531
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142489, Chloride
Region 2     
Walnut Creek
 
LOE ID: 281886
 
Pollutant: Chloride
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chloride.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chloride criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 230000 ug/L (230 mg/L)(USEPA National Recommended Water Quality Criteria, 2006).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
 
DECISION ID
142490
Region 2     
Walnut Creek
 
Pollutant: Chlorine
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282362
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282434
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282465
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282084
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282132
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282363
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282242
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282608
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282525
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282270
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282482
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142490, Chlorine
Region 2     
Walnut Creek
 
LOE ID: 282273
 
Pollutant: Chlorine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Chlorine, Total Residual.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The USEPA recommended chlorine criterion for the protection of aquatic ife in freshwater is 11 ug/L (4-day average).
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
 
DECISION ID
142491
Region 2     
Walnut Creek
 
Pollutant: Chlorpyrifos
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 270773
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Chlorpyrifos .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 93495
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chlorpyrifos.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 93496
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chlorpyrifos.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 283069
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorpyrifos. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The freshwater criterion continuous concentration to protect aquatic organisms is 0.015 ug/L (Siepmann and Finlayson 2000, with minor corrections to significant figures as described in Beaulaurier et al., 2005).
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game (with minor corrections to significant figures as described in Beaulaurier et al., 2005).
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 283035
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlorpyrifos. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The freshwater criterion continuous concentration to protect aquatic organisms is 0.015 ug/L (Siepmann and Finlayson 2000, with minor corrections to significant figures as described in Beaulaurier et al., 2005).
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game (with minor corrections to significant figures as described in Beaulaurier et al., 2005).
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142491, Chlorpyrifos
Region 2     
Walnut Creek
 
LOE ID: 270994
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Chlorpyrifos .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chlorpyrifos is the median lethal concentration (LC50) of 1.77 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Amweg and Weston, 2007).
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142533
Region 2     
Walnut Creek
 
Pollutant: Chromium
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142533, Chromium
Region 2     
Walnut Creek
 
LOE ID: 270760
 
Pollutant: Chromium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Chromium .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chromium is the probable effect concentration (PEC) of 111 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142533, Chromium
Region 2     
Walnut Creek
 
LOE ID: 93506
 
Pollutant: Chromium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chromium.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142533, Chromium
Region 2     
Walnut Creek
 
LOE ID: 93505
 
Pollutant: Chromium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chromium.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142533, Chromium
Region 2     
Walnut Creek
 
LOE ID: 271088
 
Pollutant: Chromium
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Chromium .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chromium is the probable effect concentration (PEC) of 111 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142492
Region 2     
Walnut Creek
 
Pollutant: Chrysene (C1-C4)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142492, Chrysene (C1-C4)
Region 2     
Walnut Creek
 
LOE ID: 93508
 
Pollutant: Chrysene (C1-C4)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chrysene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Chrysene is 1290 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142492, Chrysene (C1-C4)
Region 2     
Walnut Creek
 
LOE ID: 93507
 
Pollutant: Chrysene (C1-C4)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Chrysene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Chrysene is 1290 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142492, Chrysene (C1-C4)
Region 2     
Walnut Creek
 
LOE ID: 271230
 
Pollutant: Chrysene (C1-C4)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Chrysene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chrysene is the probable effect concentration (PEC) of 1290 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142492, Chrysene (C1-C4)
Region 2     
Walnut Creek
 
LOE ID: 271391
 
Pollutant: Chrysene (C1-C4)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Chrysene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for chrysene is the probable effect concentration (PEC) of 1290 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142493
Region 2     
Walnut Creek
 
Pollutant: Copper
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142493, Copper
Region 2     
Walnut Creek
 
LOE ID: 271540
 
Pollutant: Copper
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Copper .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for copper is the probable effect concentration (PEC) of 149 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142493, Copper
Region 2     
Walnut Creek
 
LOE ID: 271635
 
Pollutant: Copper
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Copper .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for copper is the probable effect concentration (PEC) of 149 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142493, Copper
Region 2     
Walnut Creek
 
LOE ID: 93513
 
Pollutant: Copper
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Copper.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142493, Copper
Region 2     
Walnut Creek
 
LOE ID: 93509
 
Pollutant: Copper
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Copper.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142530
Region 2     
Walnut Creek
 
Pollutant: Cyfluthrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 93515
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyfluthrin, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 93514
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyfluthrin, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 283419
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cyfluthrin is 0.2 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cyfluthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 283357
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cyfluthrin is 0.2 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cyfluthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 271827
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Cyfluthrin, total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 271967
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Cyfluthrin, total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 1.1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 283400
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cyfluthrin is 0.2 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cyfluthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142530, Cyfluthrin
Region 2     
Walnut Creek
 
LOE ID: 283337
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cyfluthrin is 0.2 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cyfluthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142532
Region 2     
Walnut Creek
 
Pollutant: Cyhalothrin, Lambda
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 93516
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyhalothrin, lambda, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 93517
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cyhalothrin, lambda, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 284342
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Lambda-cyhalothrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 284365
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Lambda-cyhalothrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Lambda-cyhalothrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 284324
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Lambda-cyhalothrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Lambda-cyhalothrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 284321
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Lambda-cyhalothrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 271812
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Cyhalothrin, Total lambda- .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142532, Cyhalothrin, Lambda
Region 2     
Walnut Creek
 
LOE ID: 271734
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Cyhalothrin, Total lambda- .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 0.44 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142525
Region 2     
Walnut Creek
 
Pollutant: Cypermethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 272188
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 9 samples exceeded the evaluation guideline for Cypermethrin, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al., (2002).
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 93520
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cypermethrin, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al. (2002).
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 93519
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Cypermethrin, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al. (2002).
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 283609
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cypermethrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cypermethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cypermethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 283628
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cypermethrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cypermethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cypermethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 271977
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 9 samples exceeded the evaluation guideline for Cypermethrin, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 0.3 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al., (2002).
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 283162
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cypermethrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cypermethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cypermethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142525, Cypermethrin
Region 2     
Walnut Creek
 
LOE ID: 283117
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for cypermethrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cypermethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cypermethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
148153
Region 2     
Walnut Creek
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 148153, DDD (Dichlorodiphenyldichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 272271
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for DDD (Dichlorodiphenyldichloroethane) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDD is the probable effect concentration (PEC) of 28 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148153, DDD (Dichlorodiphenyldichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 272314
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for DDD (Dichlorodiphenyldichloroethane) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDD is the probable effect concentration (PEC) of 28 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148153, DDD (Dichlorodiphenyldichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93522
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDD.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDD is 28.0 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 148153, DDD (Dichlorodiphenyldichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93521
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDD.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDD is 28.0 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
148208
Region 2     
Walnut Creek
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 148208, DDE (Dichlorodiphenyldichloroethylene)
Region 2     
Walnut Creek
 
LOE ID: 272303
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for DDE (Dichlorodiphenyldichloroethylene) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDE is the probable effect concentration (PEC) of 31.3 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148208, DDE (Dichlorodiphenyldichloroethylene)
Region 2     
Walnut Creek
 
LOE ID: 272280
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for DDE (Dichlorodiphenyldichloroethylene) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDE is the probable effect concentration (PEC) of 31.3 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148208, DDE (Dichlorodiphenyldichloroethylene)
Region 2     
Walnut Creek
 
LOE ID: 93523
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDE.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDE is 31.3 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 148208, DDE (Dichlorodiphenyldichloroethylene)
Region 2     
Walnut Creek
 
LOE ID: 93524
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDE.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDE is 31.3 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
148356
Region 2     
Walnut Creek
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 276401
 
Pollutant: Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total DDTs is the probable effect concentration (PEC) of 572 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 275879
 
Pollutant: Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total DDTs is the probable effect concentration (PEC) of 572 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 272607
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for DDT (Dichlorodiphenyltrichloroethane) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDT is the probable effect concentration (PEC) of 62.9 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 272549
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for DDT (Dichlorodiphenyltrichloroethane) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the sum of DDT is the probable effect concentration (PEC) of 62.9 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93600
 
Pollutant: Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDT, Total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for total DDTs is 572 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93610
 
Pollutant: Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and DDD)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDT, Total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for total DDTs is 572 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93526
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDT.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDT is 62.9 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 148356, DDT (Dichlorodiphenyltrichloroethane)
Region 2     
Walnut Creek
 
LOE ID: 93525
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for DDT.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for sum of DDT is 62.9 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142531
Region 2     
Walnut Creek
 
Pollutant: Deltamethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 283613
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Deltamethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 283578
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Deltamethrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 272631
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 7 samples exceeded the evaluation guideline for Deltamethrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 283579
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Deltamethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 283560
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Deltamethrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 93527
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Deltamethrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 272553
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 7 samples exceeded the evaluation guideline for Deltamethrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142531, Deltamethrin
Region 2     
Walnut Creek
 
LOE ID: 93528
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Deltamethrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 0.79 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142520
Region 2     
Walnut Creek
 
Pollutant: Dicamba
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142520, Dicamba
Region 2     
Walnut Creek
 
LOE ID: 283703
 
Pollutant: Dicamba
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dicamba.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dicamba is the USEPA Aquatic Life Benchmark of 61 ug/L for a nonvascular plant (acute) for Dicamba acid.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142520, Dicamba
Region 2     
Walnut Creek
 
LOE ID: 283720
 
Pollutant: Dicamba
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dicamba.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dicamba is the USEPA Aquatic Life Benchmark of 61 ug/L for a nonvascular plant (acute) for Dicamba acid.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142495
Region 2     
Walnut Creek
 
Pollutant: Dieldrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142495, Dieldrin
Region 2     
Walnut Creek
 
LOE ID: 272821
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Dieldrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dieldrin is the probable effect concentration (PEC) of 61.8 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142495, Dieldrin
Region 2     
Walnut Creek
 
LOE ID: 93532
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Dieldrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for dieldrin is 61.8 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142495, Dieldrin
Region 2     
Walnut Creek
 
LOE ID: 93533
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Dieldrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for dieldrin is 61.8 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142495, Dieldrin
Region 2     
Walnut Creek
 
LOE ID: 272948
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Dieldrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for dieldrin is the probable effect concentration (PEC) of 61.8 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142496
Region 2     
Walnut Creek
 
Pollutant: Diuron
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142496, Diuron
Region 2     
Walnut Creek
 
LOE ID: 283708
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Diuron.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142496, Diuron
Region 2     
Walnut Creek
 
LOE ID: 283706
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Diuron.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142496, Diuron
Region 2     
Walnut Creek
 
LOE ID: 283704
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Diuron.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142496, Diuron
Region 2     
Walnut Creek
 
LOE ID: 283707
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Diuron.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142497
Region 2     
Walnut Creek
 
Pollutant: Endrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142497, Endrin
Region 2     
Walnut Creek
 
LOE ID: 272797
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Endrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for endrin is the probable effect concentration (PEC) of 207 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142497, Endrin
Region 2     
Walnut Creek
 
LOE ID: 93534
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Endrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142497, Endrin
Region 2     
Walnut Creek
 
LOE ID: 93536
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Endrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142497, Endrin
Region 2     
Walnut Creek
 
LOE ID: 272735
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Endrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for endrin is the probable effect concentration (PEC) of 207 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142535
Region 2     
Walnut Creek
 
Pollutant: Esfenvalerate/Fenvalerate
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 273129
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Esfenvalerate/Fenvalerate, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2016-07-14
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 283514
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for esfenvalerate is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of esfenvalerate were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Esfenvalerate
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2017-06-06 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 273219
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 6 samples exceeded the evaluation guideline for Esfenvalerate/Fenvalerate, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2016-07-14
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 283571
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for esfenvalerate is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of esfenvalerate were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Esfenvalerate
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 93537
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Esfenvalerate/Fenvalerate, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 283552
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for esfenvalerate is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of esfenvalerate were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Esfenvalerate
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2017-06-06 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 283535
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for esfenvalerate is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of esfenvalerate were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Esfenvalerate
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142535, Esfenvalerate/Fenvalerate
Region 2     
Walnut Creek
 
LOE ID: 93538
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Esfenvalerate/Fenvalerate, total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142534
Region 2     
Walnut Creek
 
Pollutant: Fenpropathrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 273040
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 8 samples exceeded the evaluation guideline for Fenpropathrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al., ( 2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 93540
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fenpropathrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al. ( 2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 93539
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fenpropathrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al. ( 2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 283668
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Fenpropathrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 283645
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Fenpropathrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142534, Fenpropathrin
Region 2     
Walnut Creek
 
LOE ID: 273100
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 8 samples exceeded the evaluation guideline for Fenpropathrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 1 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al., ( 2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142518
Region 2     
Walnut Creek
 
Pollutant: Fipronil
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142518, Fipronil
Region 2     
Walnut Creek
 
LOE ID: 273006
 
Pollutant: Fipronil
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Fipronil .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil is the median lethal concentration (LC50) of 0.13 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142518, Fipronil
Region 2     
Walnut Creek
 
LOE ID: 283916
 
Pollutant: Fipronil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Fipronil. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of fipronil does not exceed 0.0032 ug/L (3.2 ng/L) in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water and Sediment Quality Criteria Report for Fipronil. Phase III: Application of the pesticide water and sediment quality criteria methodologies. Department of Environmental Toxicology, University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142518, Fipronil
Region 2     
Walnut Creek
 
LOE ID: 283835
 
Pollutant: Fipronil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Fipronil. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of fipronil does not exceed 0.0032 ug/L (3.2 ng/L) in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water and Sediment Quality Criteria Report for Fipronil. Phase III: Application of the pesticide water and sediment quality criteria methodologies. Department of Environmental Toxicology, University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142518, Fipronil
Region 2     
Walnut Creek
 
LOE ID: 273248
 
Pollutant: Fipronil
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the evaluation guideline for Fipronil .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil is the median lethal concentration (LC50) of 0.13 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142481
Region 2     
Walnut Creek
 
Pollutant: Fipronil Desulfinyl
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142481, Fipronil Desulfinyl
Region 2     
Walnut Creek
 
LOE ID: 284084
 
Pollutant: Fipronil Desulfinyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Desulfinyl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil desulfinyl is the USEPA Aquatic Life Benchmark of 0.54 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142481, Fipronil Desulfinyl
Region 2     
Walnut Creek
 
LOE ID: 283798
 
Pollutant: Fipronil Desulfinyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Desulfinyl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil desulfinyl is the USEPA Aquatic Life Benchmark of 0.54 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142481, Fipronil Desulfinyl
Region 2     
Walnut Creek
 
LOE ID: 284083
 
Pollutant: Fipronil Desulfinyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Desulfinyl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil desulfinyl is the USEPA Aquatic Life Benchmark of 0.54 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142481, Fipronil Desulfinyl
Region 2     
Walnut Creek
 
LOE ID: 284021
 
Pollutant: Fipronil Desulfinyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Desulfinyl.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil desulfinyl is the USEPA Aquatic Life Benchmark of 0.54 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142536
Region 2     
Walnut Creek
 
Pollutant: Fipronil Sulfide
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 273196
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Fipronil Sulfide .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil sulfide is the median lethal concentration (LC50) of 0.16 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 283944
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Sulfide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfide is the USEPA Aquatic Life Benchmark of 0.83 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 273348
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Fipronil Sulfide .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil sulfide is the median lethal concentration (LC50) of 0.16 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 283961
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Sulfide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfide is the USEPA Aquatic Life Benchmark of 0.83 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 283964
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Sulfide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfide is the USEPA Aquatic Life Benchmark of 0.83 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142536, Fipronil Sulfide
Region 2     
Walnut Creek
 
LOE ID: 284025
 
Pollutant: Fipronil Sulfide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Sulfide.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfide is the USEPA Aquatic Life Benchmark of 0.83 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142537
Region 2     
Walnut Creek
 
Pollutant: Fipronil Sulfone
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 283804
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Sulfone.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfone is the USEPA Aquatic Life Benchmark of 0.037 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 284046
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Fipronil Sulfone.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfone is the USEPA Aquatic Life Benchmark of 0.037 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 273554
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Fipronil Sulfone .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil sulfone is the median lethal concentration (LC50) of 0.12 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 283801
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Sulfone.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfone is the USEPA Aquatic Life Benchmark of 0.037 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 273428
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Fipronil Sulfone .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil sulfone is the median lethal concentration (LC50) of 0.12 ug/g and is normalized by the percentage of organic carbon in the sediment sample (Maul et al., 2008).
Guideline Reference: Effect of sediment-associated pyrethroids, fipronil, and metabolites on Chironomus tentans growth rate, body mass, condition index, immobilization, and survival. Environ. Toxicol. Chem. 27(12):2582-2590.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2015-06-23 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142537, Fipronil Sulfone
Region 2     
Walnut Creek
 
LOE ID: 284047
 
Pollutant: Fipronil Sulfone
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Fipronil Sulfone.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fipronil degradate fipronil sulfone is the USEPA Aquatic Life Benchmark of 0.037 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142498
Region 2     
Walnut Creek
 
Pollutant: Fluoranthene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142498, Fluoranthene
Region 2     
Walnut Creek
 
LOE ID: 273523
 
Pollutant: Fluoranthene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Fluoranthene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fluoranthene is the probable effect concentration (PEC) of 2230 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142498, Fluoranthene
Region 2     
Walnut Creek
 
LOE ID: 93544
 
Pollutant: Fluoranthene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fluoranthene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Fluoranthene is 2,230 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142498, Fluoranthene
Region 2     
Walnut Creek
 
LOE ID: 93545
 
Pollutant: Fluoranthene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fluoranthene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Fluoranthene is 2,230 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142498, Fluoranthene
Region 2     
Walnut Creek
 
LOE ID: 273379
 
Pollutant: Fluoranthene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Fluoranthene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fluoranthene is the probable effect concentration (PEC) of 2230 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142499
Region 2     
Walnut Creek
 
Pollutant: Fluorene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142499, Fluorene
Region 2     
Walnut Creek
 
LOE ID: 273487
 
Pollutant: Fluorene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 8 samples exceeded the evaluation guideline for Fluorene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fluorene is the probable effect concentration (PEC) for Fluorene is 536 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142499, Fluorene
Region 2     
Walnut Creek
 
LOE ID: 93547
 
Pollutant: Fluorene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fluorene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for fluorene is 536 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142499, Fluorene
Region 2     
Walnut Creek
 
LOE ID: 93546
 
Pollutant: Fluorene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Fluorene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for fluorene is 536 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142499, Fluorene
Region 2     
Walnut Creek
 
LOE ID: 273547
 
Pollutant: Fluorene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 8 samples exceeded the evaluation guideline for Fluorene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for fluorene is the probable effect concentration (PEC) for Fluorene is 536 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142521
Region 2     
Walnut Creek
 
Pollutant: Imidacloprid
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142521, Imidacloprid
Region 2     
Walnut Creek
 
LOE ID: 283952
 
Pollutant: Imidacloprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.
Guideline Reference: Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142521, Imidacloprid
Region 2     
Walnut Creek
 
LOE ID: 283934
 
Pollutant: Imidacloprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.
Guideline Reference: Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142521, Imidacloprid
Region 2     
Walnut Creek
 
LOE ID: 283953
 
Pollutant: Imidacloprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.
Guideline Reference: Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142521, Imidacloprid
Region 2     
Walnut Creek
 
LOE ID: 284017
 
Pollutant: Imidacloprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.
Guideline Reference: Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
148786
Region 2     
Walnut Creek
 
Pollutant: Indicator Bacteria
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299627
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 2
Number of Exceedances: 2
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2015 data for Walnut Creek to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the days of 2015-06-30 and 2015-08-04 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299823
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207R03403 (Walnut Creek, near the intersection of Civic Dr and S Carlback Ave).
Temporal Representation: The samples were collected between the days of 2017-07-24 and 2017-07-24 .
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299773
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL055 (Walnut Creek 150m South of Route 242-207WAL055).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299728
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL045 (Walnut Creek 150m North of Route 242-207WAL045).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299883
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 2
Number of Exceedances: 2
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2015 data for Walnut Creek to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the days of 2015-06-30 and 2015-08-04 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2014. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299732
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL040 (Walnut Creek 100m South of Willow Pass Rd-207WAL040).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299776
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL035 (Walnut Creek 200m North of Willow Pass Rd-207WAL035).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299793
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: 90th percentile
 
Beneficial Use: Non-Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the water quality threshold for Coliform, Fecal. The water quality threshold is based on a 30-day 90% percentile.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.1 Bacteria: Table 3-1 provides a summary of the bacterial water quality objectives and identifies the sources of those objectives. The fecal coliform objective for non-contact recreation is a 30-day 90th percentile less than 4000 MPN/100 ML.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL070 (Walnut Creek 625m North of Monument Blvd-207WAL070).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299749
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL070 (Walnut Creek 625m North of Monument Blvd-207WAL070).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299752
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL040 (Walnut Creek 100m South of Willow Pass Rd-207WAL040).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299771
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL035 (Walnut Creek 200m North of Willow Pass Rd-207WAL035).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299775
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL055 (Walnut Creek 150m South of Route 242-207WAL055).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 148786, Indicator Bacteria
Region 2     
Walnut Creek
 
LOE ID: 299774
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective to protect the REC-1 beneficial use where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 207WAL045 (Walnut Creek 150m North of Route 242-207WAL045).
Temporal Representation: The samples were collected between the days of 2013-08-15 and 2013-08-15 .
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
 
DECISION ID
142546
Region 2     
Walnut Creek
 
Pollutant: Indoxacarb
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142546, Indoxacarb
Region 2     
Walnut Creek
 
LOE ID: 283794
 
Pollutant: Indoxacarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Indoxacarb.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for indoxacarb is the USEPA Aquatic Life Benchmark of 75 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142546, Indoxacarb
Region 2     
Walnut Creek
 
LOE ID: 283793
 
Pollutant: Indoxacarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Indoxacarb.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for indoxacarb is the USEPA Aquatic Life Benchmark of 75 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142547
Region 2     
Walnut Creek
 
Pollutant: Isoxaben
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142547, Isoxaben
Region 2     
Walnut Creek
 
LOE ID: 284235
 
Pollutant: Isoxaben
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Isoxaben.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for isoxaben is the USEPA Aquatic Life Benchmark of 10 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142547, Isoxaben
Region 2     
Walnut Creek
 
LOE ID: 284236
 
Pollutant: Isoxaben
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Isoxaben.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for isoxaben is the USEPA Aquatic Life Benchmark of 10 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142500
Region 2     
Walnut Creek
 
Pollutant: Lead
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142500, Lead
Region 2     
Walnut Creek
 
LOE ID: 93556
 
Pollutant: Lead
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Lead.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for lead is 128 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142500, Lead
Region 2     
Walnut Creek
 
LOE ID: 93548
 
Pollutant: Lead
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Lead.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for lead is 128 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142500, Lead
Region 2     
Walnut Creek
 
LOE ID: 274231
 
Pollutant: Lead
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Lead .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lead is the probable effect concentration (PEC) of 128 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142500, Lead
Region 2     
Walnut Creek
 
LOE ID: 273960
 
Pollutant: Lead
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Lead .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lead is the probable effect concentration (PEC) of 128 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142501
Region 2     
Walnut Creek
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142501, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 2     
Walnut Creek
 
LOE ID: 93558
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for HCH, gamma.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for Lindane (gamma-HCH) is 4.99 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142501, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 2     
Walnut Creek
 
LOE ID: 93557
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for HCH, gamma.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for Lindane (gamma-HCH) is 4.99 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142501, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 2     
Walnut Creek
 
LOE ID: 273679
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for HCH, gamma-. Although a total of 5 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lindane is the probable effect concentration (PEC) for Lindane is 4.99 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142501, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 2     
Walnut Creek
 
LOE ID: 273638
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for HCH, gamma-. Although a total of 5 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for lindane is the probable effect concentration (PEC) for Lindane is 4.99 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142502
Region 2     
Walnut Creek
 
Pollutant: Malathion
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142502, Malathion
Region 2     
Walnut Creek
 
LOE ID: 284397
 
Pollutant: Malathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for Malathion.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of malathion does not exceed 0.028 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142502, Malathion
Region 2     
Walnut Creek
 
LOE ID: 284413
 
Pollutant: Malathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 2 samples exceeded the water quality threshold for Malathion.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Aquatic life should not be affected unacceptably if the 4-day average concentration of malathion does not exceed 0.028 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
145703
Region 2     
Walnut Creek
 
Pollutant: Mercury
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 145703, Mercury
Region 2     
Walnut Creek
 
LOE ID: 93559
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Mercury.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 145703, Mercury
Region 2     
Walnut Creek
 
LOE ID: 93560
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Mercury.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 145703, Mercury
Region 2     
Walnut Creek
 
LOE ID: 274386
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Mercury .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for mercury is the probable effect concentration (PEC) of 1.06 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 145703, Mercury
Region 2     
Walnut Creek
 
LOE ID: 274507
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Mercury .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for mercury is the probable effect concentration (PEC) of 1.06 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142503
Region 2     
Walnut Creek
 
Pollutant: Methyl Parathion
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142503, Methyl Parathion
Region 2     
Walnut Creek
 
LOE ID: 274949
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for Parathion, Methyl .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al., (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2013-06-25
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142503, Methyl Parathion
Region 2     
Walnut Creek
 
LOE ID: 93571
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Parathion, Methyl.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al. (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142503, Methyl Parathion
Region 2     
Walnut Creek
 
LOE ID: 93570
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Parathion, Methyl.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al. (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142503, Methyl Parathion
Region 2     
Walnut Creek
 
LOE ID: 274932
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 3 samples exceeded the evaluation guideline for Parathion, Methyl .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for methyl parathion is the median lethal concentration (LC50) of 6 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 6 ug/g is the geometric mean of LC50 values for methyl parathion from Ding et al., (2011).
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2013-06-25
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142482
Region 2     
Walnut Creek
 
Pollutant: Metolachlor, S-
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142482, Metolachlor, S-
Region 2     
Walnut Creek
 
LOE ID: 284578
 
Pollutant: Metolachlor, S-
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Metolachlor, S-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for metolachlor, S- is the USEPA Aquatic Life Benchmark of 8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142482, Metolachlor, S-
Region 2     
Walnut Creek
 
LOE ID: 284574
 
Pollutant: Metolachlor, S-
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Metolachlor, S-.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for metolachlor, S- is the USEPA Aquatic Life Benchmark of 8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142504
Region 2     
Walnut Creek
 
Pollutant: Naphthalene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142504, Naphthalene
Region 2     
Walnut Creek
 
LOE ID: 93573
 
Pollutant: Naphthalene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Naphthalene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for naphthalene is 561 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142504, Naphthalene
Region 2     
Walnut Creek
 
LOE ID: 93572
 
Pollutant: Naphthalene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Naphthalene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for naphthalene is 561 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142504, Naphthalene
Region 2     
Walnut Creek
 
LOE ID: 274719
 
Pollutant: Naphthalene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Naphthalene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for naphthalene is the probable effect concentration (PEC) of 561 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142504, Naphthalene
Region 2     
Walnut Creek
 
LOE ID: 274613
 
Pollutant: Naphthalene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Naphthalene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for naphthalene is the probable effect concentration (PEC) of 561 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142505
Region 2     
Walnut Creek
 
Pollutant: Nickel
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.6 of the Listing Policy. Under section 3.6 at least two lines of evidence are necessary to assess listing status for pollutants sediment, and pollutant concentrations in sediment must be associated with sediment toxicity to justify adding that pollutant to the CWA section 303(d) List.

Four lines of evidence are available in the administrative record to assess this pollutant. 2 of the 6 samples exceed the evaluation guideline. Sediment toxicity was not associated with this decision because the weight of evidence suggests nickel is not the cause of toxicity.

Based on the readily available data and information, the weight of evidence indicates that there is INSUFFICIENT justification for placing this water segment-pollutant combination on the CWA section 303(d) List.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. 2 of the 6 samples exceed the evaluation guideline and this sample size is SUFFICIENT to determine beneficial use support, with the power and confidence of the Listing Policy. However, there is not associated sediment toxicity data as required by Section 3.6 of the Listing Policy. Toxicity exceedances for the amphipod Hyalella azteca were observed, but the weight of evidence suggests nickel is not the source of toxicity. This waterbody is listed for bifenthrin and total pyrethroids and there was a stronger correlation between the number of pyrethroid exceedances and observed toxicity. Additionally, the contribution of pyrethroids to amphipod toxicity is well understood.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142505, Nickel
Region 2     
Walnut Creek
 
LOE ID: 93574
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceed the criterion for Nickel.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142505, Nickel
Region 2     
Walnut Creek
 
LOE ID: 93583
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceed the criterion for Nickel.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142505, Nickel
Region 2     
Walnut Creek
 
LOE ID: 274625
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 5 samples exceeded the evaluation guideline for Nickel .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for nickel is the probable effect concentration (PEC) of 48.6 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142505, Nickel
Region 2     
Walnut Creek
 
LOE ID: 274956
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 5 samples exceeded the evaluation guideline for Nickel .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for nickel is the probable effect concentration (PEC) of 48.6 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142523
Region 2     
Walnut Creek
 
Pollutant: Oryzalin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142523, Oryzalin
Region 2     
Walnut Creek
 
LOE ID: 285107
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oryzalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for oryzalin is the USEPA Aquatic Life Benchmark of 13 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142523, Oryzalin
Region 2     
Walnut Creek
 
LOE ID: 285106
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oryzalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for oryzalin is the USEPA Aquatic Life Benchmark of 13 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142507
Region 2     
Walnut Creek
 
Pollutant: Oxadiazon
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142507, Oxadiazon
Region 2     
Walnut Creek
 
LOE ID: 284775
 
Pollutant: Oxadiazon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oxadiazon.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Oxadiazon is the USEPA Aquatic Life Benchmark of 0.88 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142507, Oxadiazon
Region 2     
Walnut Creek
 
LOE ID: 285134
 
Pollutant: Oxadiazon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oxadiazon.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Oxadiazon is the USEPA Aquatic Life Benchmark of 0.88 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142526
Region 2     
Walnut Creek
 
Pollutant: Oxyfluorfen
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142526, Oxyfluorfen
Region 2     
Walnut Creek
 
LOE ID: 284843
 
Pollutant: Oxyfluorfen
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oxyfluorfen.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).
Guideline Reference: Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142526, Oxyfluorfen
Region 2     
Walnut Creek
 
LOE ID: 284845
 
Pollutant: Oxyfluorfen
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Oxyfluorfen.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).
Guideline Reference: Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142508
Region 2     
Walnut Creek
 
Pollutant: Oxygen, Dissolved
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286216
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286641
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286662
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286230
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286637
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286042
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 285957
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286316
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286074
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286638
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286642
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 2
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and results are as follows: 2 of 9 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2014-06-24 and 2020-07-17
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286556
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286086
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 9 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2014-06-24 and 2020-07-17
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142508, Oxygen, Dissolved
Region 2     
Walnut Creek
 
LOE ID: 286089
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
 
DECISION ID
149085
Region 2     
Walnut Creek
 
Pollutant: PAHs (Polycyclic Aromatic Hydrocarbons)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 149085, PAHs (Polycyclic Aromatic Hydrocarbons)
Region 2     
Walnut Creek
 
LOE ID: 93585
 
Pollutant: PAHs (Polycyclic Aromatic Hydrocarbons)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for PAHs (Polycyclic Aromatic Hydrocarbons).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for PAH, Total is 22,800 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 149085, PAHs (Polycyclic Aromatic Hydrocarbons)
Region 2     
Walnut Creek
 
LOE ID: 275067
 
Pollutant: PAHs (Polycyclic Aromatic Hydrocarbons)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for PAHs (Polycyclic Aromatic Hydrocarbons) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total PAHs is the probable effect concentration (PEC) of 22800 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 149085, PAHs (Polycyclic Aromatic Hydrocarbons)
Region 2     
Walnut Creek
 
LOE ID: 275110
 
Pollutant: PAHs (Polycyclic Aromatic Hydrocarbons)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for PAHs (Polycyclic Aromatic Hydrocarbons) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total PAHs is the probable effect concentration (PEC) of 22800 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 149085, PAHs (Polycyclic Aromatic Hydrocarbons)
Region 2     
Walnut Creek
 
LOE ID: 93584
 
Pollutant: PAHs (Polycyclic Aromatic Hydrocarbons)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for PAHs (Polycyclic Aromatic Hydrocarbons).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for PAH, Total is 22,800 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142511
Region 2     
Walnut Creek
 
Pollutant: PCBs (Polychlorinated biphenyls)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142511, PCBs (Polychlorinated biphenyls)
Region 2     
Walnut Creek
 
LOE ID: 90587
 
Pollutant: PCBs (Polychlorinated biphenyls)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Zero of 1 sample collected for Total PCBs exceeded the evaluation guideline.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Waters shall not contain substances in concentrations that result in the deposition of material that causes nuisance or adversely affects beneficial uses (Water Quality Control Plan for the San Francisco Bay Region).
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for total PCB is 676 ug/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected at the following station 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected on 6/17/2008.
Environmental Conditions:
QAPP Information: The SWAMP QAPP (2008) was followed.
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142511, PCBs (Polychlorinated biphenyls)
Region 2     
Walnut Creek
 
LOE ID: 275430
 
Pollutant: PCBs (Polychlorinated biphenyls)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for PCBs (Polychlorinated biphenyls) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total PCBs is the probable effect concentration (PEC) of 676 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142511, PCBs (Polychlorinated biphenyls)
Region 2     
Walnut Creek
 
LOE ID: 275072
 
Pollutant: PCBs (Polychlorinated biphenyls)
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for PCBs (Polychlorinated biphenyls) .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for total PCBs is the probable effect concentration (PEC) of 676 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2017-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142528
Region 2     
Walnut Creek
 
Pollutant: Pendimethalin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142528, Pendimethalin
Region 2     
Walnut Creek
 
LOE ID: 286373
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142528, Pendimethalin
Region 2     
Walnut Creek
 
LOE ID: 286374
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142528, Pendimethalin
Region 2     
Walnut Creek
 
LOE ID: 286393
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142528, Pendimethalin
Region 2     
Walnut Creek
 
LOE ID: 286371
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142540
Region 2     
Walnut Creek
 
Pollutant: Permethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 93586
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Permethrin, Total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 286495
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Permethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 286541
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Permethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 286612
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Permethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 275359
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Permethrin, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 275343
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Permethrin, Total .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin (Amweg et al., 2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 286423
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Permethrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142540, Permethrin
Region 2     
Walnut Creek
 
LOE ID: 93587
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Permethrin, Total.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for permethrin is the median lethal concentration (LC50) of 8.9 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin from Amweg et al. (2005).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142510
Region 2     
Walnut Creek
 
Pollutant: Phenanthrene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142510, Phenanthrene
Region 2     
Walnut Creek
 
LOE ID: 93596
 
Pollutant: Phenanthrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Phenanthrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Phenanthrene is 1170 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142510, Phenanthrene
Region 2     
Walnut Creek
 
LOE ID: 275522
 
Pollutant: Phenanthrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Phenanthrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for phenanthrene is the probable effect concentration (PEC) of 1170 ug/kg dry weight (MacDonald et al.).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142510, Phenanthrene
Region 2     
Walnut Creek
 
LOE ID: 275385
 
Pollutant: Phenanthrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Phenanthrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for phenanthrene is the probable effect concentration (PEC) of 1170 ug/kg dry weight (MacDonald et al.).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142510, Phenanthrene
Region 2     
Walnut Creek
 
LOE ID: 93597
 
Pollutant: Phenanthrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Phenanthrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Phenanthrene is 1170 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142538
Region 2     
Walnut Creek
 
Pollutant: Prodiamine
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142538, Prodiamine
Region 2     
Walnut Creek
 
LOE ID: 287487
 
Pollutant: Prodiamine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Prodiamine.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for prodiamine is the USEPA Aquatic Life Benchmark of 1.5 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142538, Prodiamine
Region 2     
Walnut Creek
 
LOE ID: 287799
 
Pollutant: Prodiamine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Prodiamine.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for prodiamine is the USEPA Aquatic Life Benchmark of 1.5 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142539
Region 2     
Walnut Creek
 
Pollutant: Propiconazole
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142539, Propiconazole
Region 2     
Walnut Creek
 
LOE ID: 287491
 
Pollutant: Propiconazole
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Propiconazole.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Propiconazole is the USEPA Aquatic Life Benchmark of 15 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142539, Propiconazole
Region 2     
Walnut Creek
 
LOE ID: 287511
 
Pollutant: Propiconazole
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Propiconazole.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for Propiconazole is the USEPA Aquatic Life Benchmark of 15 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142543
Region 2     
Walnut Creek
 
Pollutant: Pyraclostrobin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142543, Pyraclostrobin
Region 2     
Walnut Creek
 
LOE ID: 287574
 
Pollutant: Pyraclostrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Pyraclostrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pyraclostrobin is the USEPA Aquatic Life Benchmark of 1.5 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142543, Pyraclostrobin
Region 2     
Walnut Creek
 
LOE ID: 287533
 
Pollutant: Pyraclostrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Pyraclostrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pyraclostrobin is the USEPA Aquatic Life Benchmark of 1.5 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142512
Region 2     
Walnut Creek
 
Pollutant: Pyrene
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142512, Pyrene
Region 2     
Walnut Creek
 
LOE ID: 275583
 
Pollutant: Pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Pyrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pyrene is the probable effect concentration (PEC) of 1520 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142512, Pyrene
Region 2     
Walnut Creek
 
LOE ID: 93598
 
Pollutant: Pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Pyrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Pyrene is 1520 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142512, Pyrene
Region 2     
Walnut Creek
 
LOE ID: 93599
 
Pollutant: Pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Pyrene.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effects level (predictive of sediment toxicity for sediment-dwelling organisms) for Pyrene is 1520 ug/Kg dry weight (Macdonald et al. 2000)
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142512, Pyrene
Region 2     
Walnut Creek
 
LOE ID: 275665
 
Pollutant: Pyrene
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 9 samples exceeded the evaluation guideline for Pyrene .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for pyrene is the probable effect concentration (PEC) of 1520 ug/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142513
Region 2     
Walnut Creek
 
Pollutant: Simazine
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142513, Simazine
Region 2     
Walnut Creek
 
LOE ID: 288129
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Simazine.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142513, Simazine
Region 2     
Walnut Creek
 
LOE ID: 288128
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Simazine.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142514
Region 2     
Walnut Creek
 
Pollutant: Temperature, water
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298934
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298764
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298590
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 299046
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 10
Number of Exceedances: 7
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and results are as follows: 7 of 10 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2013-06-25 and 2020-07-17
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298784
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298871
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 298840
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Fish Migration
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.
Guideline Reference: EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA
Guideline Reference: U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.
Guideline Reference: Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.
Guideline Reference: Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288681
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288637
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288548
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288425
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288837
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288371
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 10
Number of Exceedances: 6
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and results are as follows: 6 of 10 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2013-06-25 and 2020-07-17
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142514, Temperature, water
Region 2     
Walnut Creek
 
LOE ID: 288479
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.
Guideline Reference: Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C
Guideline Reference: Inland Fishes of California
Guideline Reference: Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
 
DECISION ID
142527
Region 2     
Walnut Creek
 
Pollutant: Triclopyr
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142527, Triclopyr
Region 2     
Walnut Creek
 
LOE ID: 289153
 
Pollutant: Triclopyr
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Triclopyr.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for triclopyr is the USEPA Aquatic Life Benchmark of 26 ug/L for a fish (chronic) for Triclopyr Butoxyethyl Ester (BEE).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142527, Triclopyr
Region 2     
Walnut Creek
 
LOE ID: 289184
 
Pollutant: Triclopyr
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Triclopyr.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for triclopyr is the USEPA Aquatic Life Benchmark of 26 ug/L for a fish (chronic) for Triclopyr Butoxyethyl Ester (BEE).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142527, Triclopyr
Region 2     
Walnut Creek
 
LOE ID: 289150
 
Pollutant: Triclopyr
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Triclopyr.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for triclopyr is the USEPA Aquatic Life Benchmark of 26 ug/L for a fish (chronic) for Triclopyr Butoxyethyl Ester (BEE).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142527, Triclopyr
Region 2     
Walnut Creek
 
LOE ID: 289170
 
Pollutant: Triclopyr
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Triclopyr.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for triclopyr is the USEPA Aquatic Life Benchmark of 26 ug/L for a fish (chronic) for Triclopyr Butoxyethyl Ester (BEE).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: The samples were collected between the dates of 2014-03-18 and 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142542
Region 2     
Walnut Creek
 
Pollutant: Trifloxystrobin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142542, Trifloxystrobin
Region 2     
Walnut Creek
 
LOE ID: 289204
 
Pollutant: Trifloxystrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Trifloxystrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for trifloxystrobin is the USEPA Aquatic Life Benchmark of 2.76 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142542, Trifloxystrobin
Region 2     
Walnut Creek
 
LOE ID: 289188
 
Pollutant: Trifloxystrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Trifloxystrobin.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for trifloxystrobin is the USEPA Aquatic Life Benchmark of 2.76 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142516
Region 2     
Walnut Creek
 
Pollutant: Zinc
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 142516, Zinc
Region 2     
Walnut Creek
 
LOE ID: 276437
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Zinc .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for zinc is the probable effect concentration (PEC) of 459 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142516, Zinc
Region 2     
Walnut Creek
 
LOE ID: 276438
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the evaluation guideline for Zinc .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for zinc is the probable effect concentration (PEC) of 459 mg/kg dry weight (MacDonald et al., 2000a).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2018-06-27
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142516, Zinc
Region 2     
Walnut Creek
 
LOE ID: 93612
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Zinc.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for zinc is 459 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142516, Zinc
Region 2     
Walnut Creek
 
LOE ID: 93613
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Zinc.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: In freshwater sediments the probable effect concentration (predictive of sediment toxicity for sediment-dwelling organisms) for zinc is 459 mg/Kg dry weight (MacDonald et al. 2000).
Guideline Reference: Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
 
DECISION ID
142509
Region 2     
Walnut Creek
 
Pollutant: pH
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287367
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2012 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00247 (Walnut Cr_247-207R00247).
Temporal Representation: The samples were collected between the dates of 2012-05-22 and 2012-05-22
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287270
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2013 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R00567 (Tributary of Walnut Creek 55m upstream from end of Ponderosa Dr, Concord-207R00567).
Temporal Representation: The samples were collected between the dates of 2013-04-30 and 2013-04-30
Environmental Conditions:
QAPP Information: EOA, Inc.. 2012. Creek Status Monitoring Program Quality Assurance Project Plan.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287400
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2017 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01591 (Walnut Creek, near the intersection of Gehringer Dr and Bertram Ct).
Temporal Representation: The samples were collected between the dates of 2017-05-17 and 2017-05-17
Environmental Conditions:
QAPP Information: EOA, Inc., Applied Marine Sciences, Armand Ruby Consulting . 2016. BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan.
QAPP Information Reference(s): BASMAA Regional Monitoring Coalition Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287526
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 9 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2014-06-24 and 2020-07-17
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287382
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02379 (Confluence of Walnut and Moraga Creeks, 40m of the end of Bradley Avenue).
Temporal Representation: The samples were collected between the dates of 2020-06-10 and 2020-06-10
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287399
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2016 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R01271 (Walnut Creek (RMC)).
Temporal Representation: The samples were collected between the dates of 2016-05-11 and 2016-05-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2016. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status Monitoring Program Quality Assurance Project Plan
 
Line of Evidence (LOE) for Decision ID 142509, pH
Region 2     
Walnut Creek
 
LOE ID: 287401
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed BASMAA RMC Monitoring in WY2020 data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 207R02615 (Walnut Creek, 60m S of Concord Avenue nr Via De Mercados).
Temporal Representation: The samples were collected between the dates of 2020-06-11 and 2020-06-11
Environmental Conditions:
QAPP Information: EOA, Inc.. 2000. Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project.
QAPP Information Reference(s): Creek Status and Pesticides & Toxicity Monitoring Quality Assurance Project
 
 
DECISION ID
142524
Region 2     
Walnut Creek
 
Pollutant: Bifenthrin
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Sources: Other Urban Runoff | Surface Runoff
TMDL Name: San Francisco Bay Urban Creeks Diazinon
TMDL Project Code: 9
Date TMDL Approved by USEPA: 05/21/2007
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.6 of the Listing Policy. Under section 3.6 at least two lines of evidence are necessary to assess listing status for pollutants sediment, and pollutant concentrations in sediment must be associated with sediment toxicity to justify adding that pollutant to the CWA section 303(d) List.

Eleven lines of evidence are available in the administrative record to assess this pollutant. Three of the ten samples exceed the evaluation guideline. Five of nine samples exhibited sediment toxicity.

Based on the readily available data and information, the weight of evidence indicates that there is SUFFICIENT justification FOR placing this water segment-pollutant combination on the CWA section 303(d) List.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Three of the ten samples exceed the evaluation guideline and this sample size is SUFFICIENT to determine beneficial use support, with the power and confidence of the Listing Policy. There is an associated sediment toxicity data as required by Section 3.6 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 270339
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Bifenthrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin (Amweg et al., 2005 and Amweg and Weston, 2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 93492
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Bifenthrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 93483
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Bifenthrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 93611
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: One sample was collected to evaluate sediment toxicity. The sample exhibited significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 2 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. . For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.
Guideline Reference: Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064
 
Spatial Representation: The sample was collected at station 207WAL020.
Temporal Representation: The sample was collected in June 2008.
Environmental Conditions:
QAPP Information: All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 269087
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 269091
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 280557
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Bifenthrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 270300
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Bifenthrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin (Amweg et al., 2005 and Amweg and Weston, 2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 280623
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 280645
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142524, Bifenthrin
Region 2     
Walnut Creek
 
LOE ID: 280624
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Bifenthrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
 
DECISION ID
142517
Region 2     
Walnut Creek
 
Pollutant: Pyrethroids
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Sources: Other Urban Runoff | Surface Runoff
TMDL Name: San Francisco Bay Urban Creeks Diazinon
TMDL Project Code: 9
Date TMDL Approved by USEPA: 06/21/2007
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

Thirteen lines of evidence are available in the administrative record to assess this pollutant. Two of the two water samples exceed the evaluation guideline. Three of nine sediment samples exceed the evaluation guideline and there is associated sediment toxicity.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Two of the two water samples exceed the evaluation guideline and three of nine sediment samples exceed the evaluation guideline and there is associated sediment toxicity. This exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 93611
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: One sample was collected to evaluate sediment toxicity. The sample exhibited significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 2 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. . For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.
Guideline Reference: Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064
 
Spatial Representation: The sample was collected at station 207WAL020.
Temporal Representation: The sample was collected in June 2008.
Environmental Conditions:
QAPP Information: All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 269087
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287600
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287663
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287703
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287601
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287721
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 275949
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Pyrethroids .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Guideline Reference: Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids
Guideline Reference: Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287515
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 275937
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Pyrethroids .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Guideline Reference: Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids
Guideline Reference: Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287536
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 287762
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Pyrethroids.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: The samples were collected between the dates of 2016-10-14 and 2016-10-14
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142517, Pyrethroids
Region 2     
Walnut Creek
 
LOE ID: 269091
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
 
DECISION ID
142515
Region 2     
Walnut Creek
 
Pollutant: Toxicity
Final Listing Decision: List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Sources: Other Urban Runoff | Surface Runoff
TMDL Name: San Francisco Bay Urban Creeks Diazinon
TMDL Project Code: 9
Date TMDL Approved by USEPA: 05/21/2007
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.6 of the Listing Policy. Under section 3.6 a single line of evidence is necessary to assess listing status.
Three lines of evidence are available in the administrative record to assess this pollutant. Five of nine samples exceed the evaluation guideline for sediment toxicity.
Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List.
This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Five of nine samples exceed the evaluation guideline for sediment toxicity and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 270339
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Bifenthrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin (Amweg et al., 2005 and Amweg and Weston, 2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 93492
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Bifenthrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 280645
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 280557
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Bifenthrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 93483
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP data for Walnut Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Bifenthrin.
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: San Francisco Bay Basin Water Quality Control Plan 2007: All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data for this line of evidence for Walnut Creek was collected at 1 monitoring site [ Walnut Creek @ Concord Ave OC station (207WAL020)]
Temporal Representation: Data was collected on a single day 6/17/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: SWAMP data collected before September 2008 followed the QAMP (2002), however there may have been overlap in QA with SWAMP QAPP (2008).
QAPP Information Reference(s): Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
QAPP Information Reference(s): Surface Water Ambient Monitoring Program Quality Assurance Program Plan
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 270300
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Bifenthrin .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin (Amweg et al., 2005 and Amweg and Weston, 2007).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 280624
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Bifenthrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site (207WAL020).
Temporal Representation: Data for this waterbody was collected over the date range 2016-10-14 to 2017-06-06
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 275949
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Pyrethroids .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Guideline Reference: Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids
Guideline Reference: Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 93611
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: One sample was collected to evaluate sediment toxicity. The sample exhibited significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).
Data Reference: Statewide Stream Pollution Trends Study 2008
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. Region 2 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) - San Francisco Bay Region (Region 2)
 
Evaluation Guideline: Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. . For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.
Guideline Reference: Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064
 
Spatial Representation: The sample was collected at station 207WAL020.
Temporal Representation: The sample was collected in June 2008.
Environmental Conditions:
QAPP Information: All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 269087
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 269091
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 4 of the 8 samples collected by SWAMP Stream Pollution Trends for Walnut Creek exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Growth (wt/surv indiv), Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2011-07-07, Hyalella azteca for Growth (wt/surv indiv) on 2012-06-12, Hyalella azteca for Survival on 2012-06-12, Hyalella azteca for Growth (wt/surv indiv) on 2013-06-25, Hyalella azteca for Survival on 2013-06-25, Hyalella azteca for Growth (wt/surv indiv) on 2014-06-24.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms. Detrimental responses include, but are not limited to, decreased growth rate and decreased reproductive success of resident or indicator species. There shall be no acute toxicity in ambient waters. Acute toxicity is defined as a median of less than 90 percent survival, or less than 70 percent survival, 10 percent of the time, of test organisms in a 96-hour static or continuous flow test. There shall be no chronic toxicity in ambient waters. Chronic toxicity is a detrimental biological effect on growth rate, reproduction, fertilization success, larval development, population abundance, community composition, or any other relevant measure of the health of an organism, population, or community. Attainment of this objective will be determined by analyses of indicator organisms, species diversity, population density, growth anomalies, or toxicity tests (including those described in Chapter 4), or other methods selected by the Water Board. The Water Board will also consider other relevant information and numeric criteria and guidelines for toxic substances developed by other agencies as appropriate.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 207WAL020 ( Walnut Creek @ Concord Ave O.C. ).
Temporal Representation: The samples were collected between the dates of 2011-07-07 and 2020-07-17.
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 280623
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Surface Water Monitoring Project data for Walnut Creek to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The chronic criterion for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
 
Spatial Representation: The samples were collected at 1 monitoring site: Contra Costa 57 (Walnut Creek - Contra Costa).
Temporal Representation: Data for this waterbody were collected over the date range 2014-03-18 to 2014-03-18
Environmental Conditions:
QAPP Information: USEPA DPR. 2019. STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020).
QAPP Information Reference(s): STUDY 299: Pesticide Monitoring in Urban Areas of Northern California (FY 2019/2020)
 
Line of Evidence (LOE) for Decision ID 142515, Toxicity
Region 2     
Walnut Creek
 
LOE ID: 275937
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Sediment
Matrix: Sediment
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 9
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed SWAMP Stream Pollution Trends data for Walnut Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the evaluation guideline for Pyrethroids .
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.
 
SWAMP Data: SWAMP
 
Water Quality Objective/Criterion: Section 3.3.18 of the San Francisco Bay Region's Basin Plan contains the narrative toxicity objective stating that all waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce other detrimental responses in aquatic organisms.
Objective/Criterion Reference: Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)
 
Evaluation Guideline: The evaluation guideline for the protection of aquatic life from pyrethroids is one toxic unit. Individual pyrethroid concentrations in sediment were normalized to organic carbon content, divided by the respective LC50 and then summed. A sum over over one toxic unit is an exceedance of the evaluation guideline (Amweg et al. 2006).
Guideline Reference: Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5
Guideline Reference: Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15
Guideline Reference: Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.
Guideline Reference: Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.
Guideline Reference: Compilation of freshwater OC-normalized sediment toxicity data for pyrethroids
Guideline Reference: Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee. Environmental Science and Technology, 40(5): 1700-1706
 
Spatial Representation: Data were collected from 1 station(s). Station Code(s): 207WAL020 (Walnut Creek @ Concord Ave O.C.).
Temporal Representation: Data for this waterbody were collected over the date range 2011-07-07 to 2019-07-02
Environmental Conditions:
QAPP Information: SWRCB. 2018. This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements..
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.