Final California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name: Willow Slough Bypass (Yolo County)
Water Body ID: CAR5112000020080801152942
Water Body Type: River & Stream
 
DECISION ID
87150
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Malathion
Final Listing Decision: Do Not Delist from 303(d) list (being addressed with action other than TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2016)
Revision Status Revised
Sources: Agriculture
Expected Attainment Date: 2020
Implementation Action Other than TMDL: This water body segment-pollutant combination is being addressed through Basin Plan requirements established under CRWQCB-CVR resolution R5-2014-0030-06 and implemented through Board established Waste Discharge Requirements for agricultural discharges. The sources of malathion to this waterbody segment have been identified as offsite movement of malathion from malathion applications by the agricultural dischargers regulated by the CRWQCB-CVR WDRs and non-agricultural applications. The WDRs include a time schedule, milestones and a monitoring and reporting program. The WDRs require growers to develop and implement water quality management plans iteratively to attain water quality objectives as soon as possible, but no later than ten years from the identification of water quality exceedances. The WDRs monitoring and reporting program requires growers to regularly monitor water bodies with management plans to assess progress at meeting standards and regularly report monitoring results to the Regional Board. A management plan for malathion in Willow Slough was developed in 2010 and completed in 2017. Agricultural management practices being used to reduce offsite movement of malathion into surface water include alternative weed management practices, pesticide application practices, vegetation management and water management practices, all of which are effective in reducing offsite movement of malathion into surface water. The WDRs require management practices to be iteratively improved through updates of the management plans until water quality criteria are achieved. The malathion criteria are expected to be attained through continued implementation and improvement of management practices within the required 10-year compliance time frame.
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 4.11 of the Listing Policy. Under section 4.11 of the Policy, a minimum of one line of evidence is needed to assess listing status. One line of evidence is 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 section 303(d) List because the RWQCB has determined that an existing regulatory program is reasonably expected to result in attainment of the standard within a reasonable, specified time frame.
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 19 samples exceeded the evaluation guideline for malathion and these exceed the allowable frequency listed in Table 4.1 of the Listing Policy.
4. The Irrigated Lands Regulatory Program resolution R5-2014-003-06 has been approved by the RWQCB-CVR in 2014 and a management plan was developed in 2010 for Willow Slough. The management plan was completed in 2017 and is expected to attain applicable water quality standards.
5. Willow Slough was originally identified as impaired by malathion in 2014.
6. Agricultural management practices implemented include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which were effective in reducing offsite movement of malathion into surface water.
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:
 
 
Line of Evidence (LOE) for Decision ID 87150, Malathion
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72450
 
Pollutant: Malathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 3
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 3 of 19 samples exceed the criterion for Malathion.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Basin Plan states: "Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide..." Aquatic life should not be affected unacceptably if the 4-day average concentration of Malathion, 0.028 ug/L, is not exceeded more than once every three years on the average (UC Davis Aquatic Life Criterion).
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128897
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Aldicarb
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 3.1 of the Listing Policy.

Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy).

LOE 72622 has been replaced by LOE 221406 and LOE 221405 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy.

Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.
 
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 128897, Aldicarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221406
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Aldicarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Aldicarb is the USEPA Aquatic Life Benchmark of 0.46 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128897, Aldicarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72623
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 9 samples exceed the criterion for Aldicarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Department of Public Health archived advisory level for aldicarb is 7 ug/L.
Guideline Reference: CDPH Archived Advisory Levels for Drinking Water. Archived Advisory Levels are currently considered Notification Levels.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128897, Aldicarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221405
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Aldicarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Aldicarb is the USEPA Aquatic Life Benchmark of 0.46 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128876
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Atrazine
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.

LOE 72671 has been replaced by LOE 221680 and 221730 due to a reassessment of data using a U.S. EPA aquatic life benchmark
 
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 128876, Atrazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221730
 
Pollutant: Atrazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Atrazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of <1 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128876, Atrazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72672
 
Pollutant: Atrazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 14
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 14 samples exceed the criterion for Atrazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for atrazine is 1 ug/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128876, Atrazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221680
 
Pollutant: Atrazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Atrazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of <1 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128885
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Bromacil
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the sixteen samples exceed the evaluation guideline for WARM. LOE 72699 has been replaced by LOE 221535 and LOE 221557 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

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. Zero of the sixteen samples exceed the evaluation guideline for WARM and this does not exceed 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 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:
 
 
Line of Evidence (LOE) for Decision ID 128885, Bromacil
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221535
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Bromacil.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128885, Bromacil
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221557
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Bromacil.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128877
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Dacthal
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.

LOE 79538 has been replaced by LOE 221650 and LOE 221652 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128877, Dacthal
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221650
 
Pollutant: Dacthal
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Dacthal.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dacthal is the USEPA Aquatic Life Benchmark of >1100 ug/L for a nonvascular plant (acute) and vascular plant (acute). The benchmark was derived from a \greater-than\" value (for example, > 265,000) and may overestimate toxicity."
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-04-17 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128877, Dacthal
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221652
 
Pollutant: Dacthal
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Dacthal.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dacthal is the USEPA Aquatic Life Benchmark of >1100 ug/L for a nonvascular plant (acute) and vascular plant (acute). The benchmark was derived from a \greater-than\" value (for example, > 265,000) and may overestimate toxicity."
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-01-28
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128878
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Dicofol
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. LOE 72325 has been replaced by LOE 221524 and LOE 221686 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128878, Dicofol
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221686
 
Pollutant: Dicofol
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Dicofol.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dicofol is the USEPA Aquatic Life Benchmark of 4.4 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128878, Dicofol
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221524
 
Pollutant: Dicofol
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Dicofol.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dicofol is the USEPA Aquatic Life Benchmark of 4.4 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128891
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Dimethoate
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 3.1 of the Listing Policy.

Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Line of evidence #72328 was replaced by #221644 and #221646.

Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy).

The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy.

Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.
 
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 128891, Dimethoate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221646
 
Pollutant: Dimethoate
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Dimethoate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128891, Dimethoate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221644
 
Pollutant: Dimethoate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 12 samples exceeded the water quality threshold for Dimethoate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2009-09-22
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128894
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Ethoprop
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 3.1 of the Listing Policy.

Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy).

LOE 72385 has been replaced by LOE 222020 and LOE 222022 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy.

Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.
 
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 128894, Ethoprop
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222020
 
Pollutant: Ethoprop
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 12 samples exceeded the water quality threshold for Ethoprop.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Ethoprop is the USEPA Aquatic Life Benchmark of 0.8 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2009-09-22
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128894, Ethoprop
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222022
 
Pollutant: Ethoprop
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Ethoprop.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Ethoprop is the USEPA Aquatic Life Benchmark of 0.8 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128879
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Glyphosate
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.

LOE 72387 has been replaced by LOEs 221814 and 221855 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128879, Glyphosate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221814
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Glyphosate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128879, Glyphosate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72388
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 14
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 14 samples exceed the criterion for Glyphosate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for Glyphosate is 700 ug/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128879, Glyphosate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221855
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Glyphosate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128880
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Linuron
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.

LOE 72449 has been replaced by LOE 221794 and LOE 221838 due to a reassessment of data using a U.S. EPA aquatic life benchmark
 
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 128880, Linuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221794
 
Pollutant: Linuron
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Linuron. Although a total of 8 samples were collected, 8 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: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP).
Temporal Representation: Date for this waterbody was collected over the date range 2007-02-10 to 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128880, Linuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221838
 
Pollutant: Linuron
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Linuron. Although a total of 8 samples were collected, 8 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: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL).
Temporal Representation: Date for this waterbody was collected over the date range 2008-01-28 to 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128889
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Methidathion
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the eighteen samples exceed the evaluation guideline for COLD. LOE 72451 has been replaced by LOE 221758 and LOE 222051 due to a reassessment of data using a U.S. EPA aquatic life benchmark

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

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. Zero of the eighteen samples exceed the evaluation guideline for COLD and this does not exceed 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 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 128889, Methidathion
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 221758
 
Pollutant: Methidathion
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Methidathion.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Methidathion is the USEPA Aquatic Life Benchmark of 0.66 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128889, Methidathion
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222051
 
Pollutant: Methidathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 11
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 11 samples exceeded the water quality threshold for Methidathion.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Methidathion is the USEPA Aquatic Life Benchmark of 0.66 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-04-21 and 2009-09-22
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128886
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Methiocarb
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 3.1 of the Listing Policy.

Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy).

The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy.

Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

LOE 72479 has been replaced by LOEs 222037 and 222081 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128886, Methiocarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222081
 
Pollutant: Methiocarb
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Methiocarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Methiocarb is the USEPA Aquatic Life Benchmark of 2.75 ug/L for a invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128886, Methiocarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222037
 
Pollutant: Methiocarb
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Methiocarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Methiocarb is the USEPA Aquatic Life Benchmark of 2.75 ug/L for a invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128881
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Molinate
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.

LOE 72515 has been replaced by LOE 222415 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128881, Molinate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222415
 
Pollutant: Molinate
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Molinate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The California Department of Fish and Wildlife hazard assessment instantaneous criterion (1-hour average) for the protection of aquatic life for Molinate is 13 ug/L.
Guideline Reference: Hazard Assessment of the Rice Herbicides Molinate and Thiobencarb to Aquatic Organisms in the Sacramento River System. Administrative Report 90-1. California Department of Fish and Game, Environmental Services Division
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128881, Molinate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72516
 
Pollutant: Molinate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceed the criterion for Molinate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for Molinate is 20 ug/L .
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-12/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128887
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Oryzalin
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: Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Line of evidence #72554 was replaced by #222147 and #222150.

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 128887, Oryzalin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222147
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Oryzalin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128887, Oryzalin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222150
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Oryzalin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128892
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Oxyfluorfen
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.

LOE 72555 has been replaced by LOE 222221 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128892, Oxyfluorfen
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222221
 
Pollutant: Oxyfluorfen
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Oxyfluorfen.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Oxyfluorfen is the USEPA Aquatic Life Benchmark of 0.29 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128895
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Pendimethalin
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.

LOE 72579 has been replaced by LOE 222164 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128895, Pendimethalin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222164
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128896
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Phorate
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 3.1 of the Listing Policy.

Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy).

The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy.

Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

LOE 72580 has been replaced by LOEs 222328 and 222349 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128896, Phorate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222328
 
Pollutant: Phorate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 12
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 12 samples exceeded the water quality threshold for Phorate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2009-09-22
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128896, Phorate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222349
 
Pollutant: Phorate
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Phorate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128898
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Phosmet
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the eighteen samples exceed the evaluation guideline. LOE 72581 has been replaced by LOEs 222336 and 222295 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

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. Zero of the eighteen samples exceed the evaluation guideline and this does not exceed 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 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:
 
 
Line of Evidence (LOE) for Decision ID 128898, Phosmet
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222336
 
Pollutant: Phosmet
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Phosmet.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Phosmet is the USEPA Aquatic Life Benchmark of 0.8 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128898, Phosmet
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222295
 
Pollutant: Phosmet
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 11
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 11 samples exceeded the water quality threshold for Phosmet.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Phosmet is the USEPA Aquatic Life Benchmark of 0.8 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-04-21 and 2009-09-22
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128882
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Prometon (Prometone)
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. LOE 72602 has been replaced by LOE 222184 and LOE 222162 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128882, Prometon (Prometone)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222162
 
Pollutant: Prometon (Prometone)
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Prometon.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Prometon (Prometone) is the USEPA Aquatic Life Benchmark of 98 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128882, Prometon (Prometone)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222184
 
Pollutant: Prometon (Prometone)
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Prometon.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Prometon (Prometone) is the USEPA Aquatic Life Benchmark of 98 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128890
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Prometryn
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.

LOE 72603 has been replaced by LOE 222207 and LOE 222253 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128890, Prometryn
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222207
 
Pollutant: Prometryn
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Prometryn.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Prometryn is the USEPA Aquatic Life Benchmark of 1.04 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128890, Prometryn
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222253
 
Pollutant: Prometryn
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Prometryn.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Prometryn is the USEPA Aquatic Life Benchmark of 1.04 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128893
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Propargite
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.

LOE 72604 has been replaced by LOE 222297 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128893, Propargite
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222297
 
Pollutant: Propargite
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Propargite.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Propargite is the USEPA Aquatic Life Benchmark of 7 ug/L for a invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128899
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Propazine
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.

LOE 72605 has been replaced by LOE 222344 and LOE 222342 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128899, Propazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222344
 
Pollutant: Propazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Propazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Propazine is the USEPA Aquatic Life Benchmark of 24.8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128899, Propazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222342
 
Pollutant: Propazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Propazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Propazine is the USEPA Aquatic Life Benchmark of 24.8 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128883
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Simazine
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.

LOE 72629 has been replaced by LOE 222572 and LOE 222431 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128883, Simazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222572
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Simazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128883, Simazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222431
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Simazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
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 (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128883, Simazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72630
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 14
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 14 samples exceed the criterion for Simazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for Simazine is 4 ug/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128888
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Tebuthiuron
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the sixteen samples exceed the evaluation guideline. LOE 72649 has been replaced by LOEs 222531 and 222527 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

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. Zero of sixteen samples exceeded the Evaluation Guideline and this does not exceed 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 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:
 
 
Line of Evidence (LOE) for Decision ID 128888, Tebuthiuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222527
 
Pollutant: Tebuthiuron
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Tebuthiuron.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Tebuthiuron is the USEPA Aquatic Life Benchmark of 50 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 128888, Tebuthiuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222531
 
Pollutant: Tebuthiuron
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Tebuthiuron.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Tebuthiuron is the USEPA Aquatic Life Benchmark of 50 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSPL)
Temporal Representation: The samples were collected between the dates of 2008-01-28 and 2008-09-15
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128900
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Thiobencarb
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:
 
 
Line of Evidence (LOE) for Decision ID 128900, Thiobencarb
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222590
 
Pollutant: Thiobencarb
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Thiobencarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Thiobencarb is the USEPA Aquatic Life Benchmark of 1 ug/L for a invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
128884
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Trifluralin
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.

LOE 72677 has been replaced by LOE 222537 due to a reassessment of data using a U.S. EPA aquatic life benchmark.
 
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 128884, Trifluralin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 222537
 
Pollutant: Trifluralin
LOE Subgroup: Pollutant-Water
Matrix: Water
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 ILRP_SVWQC data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Trifluralin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for Trifluralin is the USEPA Aquatic Life Benchmark of 1.9 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (511XWLSBP)
Temporal Representation: The samples were collected between the dates of 2007-02-10 and 2007-12-19
Environmental Conditions:
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
71702
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Boron
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)(2016)
Revision Status Original
Sources: A Source Unknown
Expected TMDL Completion Date: 2021
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status.

Three lines of evidence are available in the administrative record to assess pollutant. Twenty-one of the 22 samples exceed the evaluation guideline.

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.

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. Twenty-one of 22 samples exceeded the evaluation guideline and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy.
4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are 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 71702, Boron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79537
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Agricultural Supply
 
Number of Samples: 16
Number of Exceedances: 15
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 15 of 16 samples exceed the criterion for Boron.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. At or below the limits presented in the Water Quality Goals tables, agricultural uses of water should not be limited. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The criteria for boron is 700 ug/L (0.7 mg/L).
Guideline Reference: Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 71702, Boron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23284
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Agricultural Supply
 
Number of Samples: 6
Number of Exceedances: 6
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: The Quality Assurance Project Plan for Water Quality Monitoring for the Yolo Bypass Watershed Planning Project (QAPP; LWA, 2003) indicates that water samples were planned to be collected from Willow Slough Bypass approximately bimonthly between November 22 2003 and September 22 2004. According to the QAPP, three separate water samples were to be collected at Willow Slough Bypass on 1/23/2004 - one each primary, field duplicate (FD), and field blank (FB). However, the data provided indicates that only a primary and a -FB- sample were collected. The primary and -FB- sample results are identical, both for total and dissolved boron. The results for the samples collected on 1/23/2004 are similar in magnitude to the primary sample results for samples collected in Willow Slough Bypass on the other sample dates. It appears reasonable that the data reported for samples collected from Willow Slough Bypass on 1/23/2004 are for the primary and duplicate samples and 6 of 6 total Boron concentrations exceeded the evaluation guideline for Boron.
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life (CVRWQCB, 2007).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: Boron levels should not exceed the Agricultural Water Quality Goal for Boron of 700 ug/L (Ayers and Westcott, 1985).
Guideline Reference: Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)
 
Spatial Representation: Samples were collected at the lower end of Willow Slough Bypass.
Temporal Representation: Samples were collected approximately bimonthly from November 22 2003 to September 22 2004. Willow Slough Bypass extends from Willow Slough near the Southern Pacific Railroad bridge, eastward to the Yolo Bypass.
Environmental Conditions:
QAPP Information: Data quality: Questionable. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 71702, Boron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23285
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Agricultural Supply
 
Number of Samples: 6
Number of Exceedances: 6
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: The Quality Assurance Project Plan for Water Quality Monitoring for the Yolo Bypass Watershed Planning Project (QAPP; LWA, 2003) indicates that water samples were planned to be collected from Willow Slough Bypass approximately bimonthly between November 22 2003 and September 22 2004. According to the QAPP, three separate water samples were to be collected at Willow Slough Bypass on 1/23/2004 - one each primary, field duplicate (FD), and field blank (FB). However, the data provided indicates that only a primary and a -FB- sample were collected. The primary and -FB- sample results are identical, both for total and dissolved boron. The results for the samples collected on 1/23/2004 are similar in magnitude to the primary sample results for samples collected in Willow Slough Bypass on the other sample dates. It appears reasonable that the data reported for samples collected from Willow Slough Bypass on 1/23/2004 are for the primary and duplicate samples and 6 of 6 dissolved Boron concentrations exceeded the evaluation guideline for Boron.
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life (CVRWQCB, 2007).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: Boron levels should not exceed the Agricultural Water Quality Goal for Boron of 700 ug/L (Ayers and Westcott, 1985).
Guideline Reference: Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)
 
Spatial Representation: Samples were collected at the lower end of Willow Slough Bypass.
Temporal Representation: Samples were collected approximately bimonthly from November 22 2003 to September 22 2004. Willow Slough Bypass extends from Willow Slough near the Southern Pacific Railroad bridge, eastward to the Yolo Bypass.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
 
DECISION ID
72424
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Indicator Bacteria
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)(2016)
Revision Status Original
Sources: A Source Unknown
Expected TMDL Completion Date: 2027
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status.

Four lines of evidence are available in the administrative record to assess this pollutant. Twenty of the 38 samples exceed the evaluation guideline for Escherichia coli. Eleven of the 15 samples exceed the evaluation guideline for fecal coliform.

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.

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. Twenty of 38 samples exceeded the evaluation guideline for Escherichia coli, and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. Eleven of 15 samples exceeded the evaluation guideline for fecal coliform, and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy.
4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are 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 72424, Indicator Bacteria
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23279
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 13
Number of Exceedances: 11
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: The Yolo Bypass Watershed Planning Program collected 13 samples from November 2003 to October 2004. Eleven of the 13 samples exceeded the evaluation objective.
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: In waters designated for contact recreation (REC-1), the E. coli concentration, based on a minimum of not less than five samples equally spaced over a 30-day period, shall not exceed a geometric mean of 126 MPN/100 mL and shall not exceed 235 MPN /100 mL in any single sample.
Guideline Reference: Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
 
Spatial Representation: Samples were collected from Willow Slough.
Temporal Representation: Sampling occurred from November 2003 to October 2004.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 72424, Indicator Bacteria
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23265
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 12
Number of Exceedances: 10
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: The Yolo Bypass Watershed Planning Program collected 10 samples from November 2003 to October 2004. The geometric mean per month per site was calculated from the samples and 10 out of the 12 calculated geometric means exceeded the evaluation objective.
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: In waters designated for contact recreation (REC-1), the fecal coliform concentration based on a minimum of not less than five samples for any 30-day period shall not exceed a geometric mean of 200/100 ml, nor shall more than ten percent of the total number of samples taken during any 30-day period exceed 400/100 ml.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected from Willow Slough Bypass.
Temporal Representation: Sampling occurred from November 2003 to October 2004
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 72424, Indicator Bacteria
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72384
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 25
Number of Exceedances: 9
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 9 of 25 samples exceed the criterion for Escherichia coli.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River and San Joaquin River Basins)
Objective/Criterion Reference: Water Quality Control Plan for the Tulare Lake Basin Second Edition. rev. Jan 2004
 
Evaluation Guideline: The USEPA recommended objective for single sample maximum allowable density of E. coli in freshwater designated beach areas is 235 MPN/100mL.
Guideline Reference: Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 72424, Indicator Bacteria
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72386
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 3
Number of Exceedances: 1
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 1 of 3 samples exceed the criterion for Coliform, Fecal.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: In waters designated for contact recreation (REC-1), the fecal coliform concentration based on a minimum of not less than five samples for any 30-day period shall not exceed a geometric mean of 200/100 ml, nor shall more than ten percent of the total number of samples taken during any 30-day period exceed 400/100 ml. (Water Quality Control Plan, Central Valley Region, Tulare Lake Basin)
Objective/Criterion Reference: Water Quality Control Plan for the Tulare Lake Basin Second Edition. rev. Jan 2004
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at Pole Line - 511XWLSPL]
Temporal Representation: Data was collected over the time period 4/23/2009-6/16/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90843
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Aldrin
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of sixteen samples exceed the criterion maximum concentration to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 0 samples exceed the CTR objective to protect human health from the consumption of water and organisms for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of sixteen samples exceed the criterion maximum concentration to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 0 samples exceed the CTR objective to protect human health from the consumption of water and organisms for MUN, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90843, Aldrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72624
 
Pollutant: Aldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Aldrin. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The CTR objective for aldrin to protect human health from the consumption of water and organisms is 0.00013 ug/L.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 90843, Aldrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72643
 
Pollutant: Aldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Aldrin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The criterion maximum concentration to protect aquatic life in freshwater for aldrin is 1.5 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
86985
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Aluminum
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)(2016)
Revision Status Original
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 and using Table 3.1 of the Listing Policy. Under section 3.1, a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 2 samples exceed the COLD water Evaluation Guideline, zero of the 2 samples exceed the MUN water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 2 samples exceed the COLD water Evaluation Guideline, zero of 2 samples exceed the MUN water quality objective, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 86985, Aluminum
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72647
 
Pollutant: Aluminum
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Aluminum.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California secondary maximum contaminant level for aluminum is 0.2 mg/L.
Objective/Criterion Reference: Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 5/15/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 86985, Aluminum
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79536
 
Pollutant: Aluminum
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
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: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Aluminum.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: 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.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The National Recommended Water Quality Critiera for the protection of aquatic life is the chronic continuous concentration (expressed as a 4-day average) of 87 ug/L.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 5/15/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
94338
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Ammonia as N, Total
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)(2016)
Revision Status Original
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, one line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the 24 water sample ammonia concentrations exceed the calculated CMC evaluation guideline.
Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. None of the 24 water sample ammonia concentrations exceed the calculated CMC evaluation guideline, and this sample size is sufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples are needed to determine if a beneficial use is fully supported using table 3.1.
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 this water body and pollutant combination should not be placed on the section 303(d) list. The readily available data and information is sufficient 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 94338, Ammonia as N, Total
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79036
 
Pollutant: Ammonia as N, Total
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Cold Freshwater Habitat
Aquatic Life Use: Cold Freshwater Habitat
 
Number of Samples: 24
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Twenty-four water samples collected from Willow Slough Bypass (Yolo County) by the Sacramento Valley Water Quality Coalition were analyzed for ammonia, pH and temperature. None of the 24 sample results exceeded the calculated ammonia CMC values.
Data Reference: Data for Various Pollutants in Southern San Joaquin Water Quality Coalition, 2004-2009.
 
SWAMP Data:
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. This objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: Per the National Recommended Water Quality Criteria (USEPA 2006): The 1-hour average concentration (acute criterion or CMC) of total ammonia nitrogen (in mg N/L) for freshwater where salmonid fish are present, which is not to be exceeded more than once every three years on average, is calculated using the following equation: CMC=0.275/(1+10^(7.204 - pH)) + 39.0/(1+10^(pH - 7.204)).
Guideline Reference: Data for Various Pollutants in South San Joaquin Irrigation District, 2004-2008.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: The 24 water samples were collected from Willow Slough Bypass (Yolo County) at two monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL and Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: The 24 water samples were collected from Willow Slough Bypass (Yolo County) between 2/10/2007 and 9/22/2009
Environmental Conditions:
QAPP Information: Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.
QAPP Information Reference(s):
 
 
DECISION ID
95576
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of sixteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 16 samples exceed the California Primary MCL for MUN.

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

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. Zero of sixteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 16 samples exceed the California Primary MCL for MUN and this does not exceed 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 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 95576, Arsenic
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72670
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Arsenic.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater for dissolved arsenic is 0.150 mg/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 95576, Arsenic
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72648
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Arsenic.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for arsenic is 0.010 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90898
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Azinphos-methyl (Guthion)
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the zero samples exceed the Evaluation Guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceeded Evaluation Guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90898, Azinphos-methyl (Guthion)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72673
 
Pollutant: Azinphos-methyl (Guthion)
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Azinphos methyl. Eighteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The National Recommended Water Quality criterion for Azinphos Methyl (Guthion) for the protection of freshwater aquatic life is a maximum of 0.01 ug/l.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90899
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Benomyl
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Evaluation Guideline.

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

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. Zero of 16 samples exceeded the Evaluation Guideline and this does not exceed 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 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 90899, Benomyl
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72674
 
Pollutant: Benomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: The data was assessed using the CDFW-derived aquatic life criterion for Benomyl of 8.8 µg/L (1-hour average); 0 of 16 samples exceed the criterion for Benomyl.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The California Department of Fish and Wildlife instantaneous criterion (1-hour average) for Benomyl is 8.8 ug/L.
Guideline Reference: Hazard Assessment of the Fungicides Benomyl, Captan, Chlorothalonil, Maneb, and Ziram to Aquatic Organisms
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87038
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of sixteen samples exceed CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 16 samples exceed the California Primary MCL for MUN.

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

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. Zero of sixteen samples exceed CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 16 samples exceed the California Primary MCL for MUN and this does not exceed 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 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 87038, Cadmium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72700
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Cadmium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for cadmium is 5 ug/L.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 87038, Cadmium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72701
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Cadmium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The cadmium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for the metals criterion.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87039
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Carbaryl
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Evaluation Guideline.

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

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. Zero of 16 samples exceeded the Evaluation Guideline and this does not exceed 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 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 87039, Carbaryl
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72268
 
Pollutant: Carbaryl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Carbaryl.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The USEPA recommended water quality criterion for freshwater aquatic life for carbaryl is 2.1 µg/L.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90955
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Carbofuran
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. One of the 16 samples exceed the COLD water Evaluation Guideline, zero of the 16 samples exceed the MUN water quality objective.

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

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. One of the 16 samples exceed the COLD water Evaluation Guideline, zero of the 16 samples exceed the MUN water quality objective, and this does not exceed 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 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 90955, Carbofuran
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72269
 
Pollutant: Carbofuran
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 1 of 16 samples exceed the criterion for Carbofuran.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The freshwater criterion maximum concentration for carbofuran is 0.5 µg/L (DFG 92-3, 1992).
Guideline Reference: Hazard Assessment of the Insecticide Carbofuran to Aquatic Organisms in the Sacramento River System
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 90955, Carbofuran
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72270
 
Pollutant: Carbofuran
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Carbofuran.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for Carbofuran is 18 ug/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87091
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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 3.1a one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 3 samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 3 samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 87091, Chromium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72272
 
Pollutant: Chromium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
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 agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Chromium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87092
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of sixteen samples exceed the CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 16 samples exceed the California Secondary MCL for MUN.

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

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. Zero of sixteen samples exceed the CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 16 samples exceed the California Secondary MCL for MUN and this does not exceed 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 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 87092, Copper
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72273
 
Pollutant: Copper
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Copper.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California secondary maximum contaminant level for copper is 1.0 mg/L.
Objective/Criterion Reference: Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 87092, Copper
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72298
 
Pollutant: Copper
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Copper.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90956
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Cyanazine
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the one samples exceed the Evaluation Guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of one samples exceeded Evaluation Guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90956, Cyanazine
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72299
 
Pollutant: Cyanazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 14
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 14 samples exceed the criterion for Cyanazine.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The EC50 for Navicula pelliculosa (freshwater diatom) for cyanazine is 4.8 ug/L (USEPA Office of Pesticide Programs Ecotoxicity database).
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
72098
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: The decision has not changed. Region 5 data was not included in the 2012 Integrated Report so all decisions are carried over from the 2010 listing cycle.

This pollutant is being considered for placement on the 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.

One line(s) of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

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. Zero of 2 samples exceeded the water quality objective and this does not exceed 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: This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.
 
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 72098, DDD (Dichlorodiphenyldichloroethane)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23272
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Five water samples were collected from Willow Slough between November 2003 and June 2004. None of the Five samples exceed the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 ug/L for DDD based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms. - Three samples had a high Reporting Limit hence the data could not be used in the analysis for exceedance (Listing Policy, Section 6.5.1.1) (SWRCB, 2004).
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007)Pesticides: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000)Inland Surface Waters based on drinking water and aquatic organism consumption. The criteria are based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) with a limit of 0.00083 ug/L for DDD.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected from an input channel of Willow Slough Bypass in Yolo County, California.
Temporal Representation: Samples were collected between November 2003 and September 2004 at irregular intervals.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
 
DECISION ID
72379
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: The decision has not changed. Region 5 data was not included in the 2012 Integrated Report so all decisions are carried over from the 2010 listing cycle.

This pollutant is being considered for placement on the 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.

One line(s) of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category.

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. None of 5 samples exceeded the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 &#956;g/L for total DDE based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms and this does not exceed 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: This is a decision previously approved by the State Water Resources Control Board and the USEPA. No new data were assessed by the Regional Board for the current cycle. The decision has not changed.
 
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 72379, DDE (Dichlorodiphenyldichloroethylene)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23273
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Five samples were collected from Willow Slough between November 2003 and June 2004. None of the Five samples exceed the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 ug/L for DDE based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms. - All samples had a high Reporting Limit hence the data could not be used in the analysis for exceedance (Listing Policy, Section 6.5.1.1) (SWRCB, 2004).
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Toxics Rule Criterion for Inland Surface Waters based on drinking water and aquatic organism consumption. The criterion is based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) with a limit of 0.00059 ug/L for DDE (USEPA, 2000).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected from an input channel of Willow Slough Bypass in Yolo County, California.
Temporal Representation: Samples were collected between November 2003 and September 2004 at irregular intervals.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
 
DECISION ID
73305
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Three lines of evidence are available in the administrative record to assess this pollutant. Zero of zero samples exceed the criterion continuous concentration to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 0 samples exceed the criterion to protect human health from consumption of water and organisms (CTR) for MUN, and 0 of 6 samples exceed the zero of the six samples exceed the CTR Criterion for Inland Surface Waters based on drinking water and aquatic organism consumption for the protection of human health for carcinogenicity (USEPA, 2000) for COMM.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceed the criterion continuous concentration to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 0 samples exceed the criterion to protect human health from consumption of water and organisms (CTR) for MUN, and 0 of 6 samples exceed the zero of the six samples exceed the CTR Criterion for Inland Surface Waters based on drinking water and aquatic organism consumption for the protection of human health for carcinogenicity (USEPA, 2000) for COMM, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 73305, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72301
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: The reporting limit is greater than the criterion; therefore, the results of the samples were not assessed. 0 of 0 samples exceed the criterion for DDT (Dichlorodiphenyltrichloroethane).
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The DDT criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected monthly between 2/10/2007 and 9/15/2008. One pair of samples were collected on the same date; the results were averaged.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 73305, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72300
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: The reporting limit is greater than the criterion; therefore, the results of the samples were not assessed. 0 of 0 samples exceed the criterion for DDT (Dichlorodiphenyltrichloroethane).
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The criterion for total DDT to protect human health from consumption of water and organisms is 0.00059 ug/L (California Toxics Rule).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected monthly between 2/10/2007 and 9/15/2008. One pair of samples were collected on the same date; the results were averaged.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 73305, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23274
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Six water samples were collected from Willow Slough between November 2003 and June 2004. None of the Six samples exceed the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 ug/L for DDT based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms. - Five water samples had a high Reporting Limit hence the data was not used in the analysis for exceedance (Listing Policy, Section 6.5.1.1) (SWRCB, 2004).
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Toxics Rule Criterion for Inland Surface Waters based on drinking water and aquatic organism consumption. The criterion is based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) with a limit of 0.00059 ug/L for DDT (USEPA, 2000).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected from an input channel of Willow Slough Bypass in Yolo County, California.
Temporal Representation: Samples were collected between November 2003 and September 2004 at irregular intervals.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
 
DECISION ID
90958
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Demeton
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 13 samples exceed the Evaluation Guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 13 samples exceeded Evaluation Guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90958, Demeton
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72302
 
Pollutant: Demeton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 13
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 13 samples exceed the criterion for Demeton.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The USEPA Recommended Water Aquatic Life criterion continuous concentration for demeton in freshwater is 0.1 ug/L.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87093
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Diazinon
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 19 samples exceed the Evaluation Guideline.

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

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. Zero of 19 samples exceeded the Evaluation Guideline and this does not exceed 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 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 87093, Diazinon
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72324
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 19 samples exceed the criterion for Diazinon.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The freshwater chronic criterion value for diazinon is 0.1 ug/L, expressed as a continuous concentration (Finlayson, 2004).
Guideline Reference: Water quality for diazinon. Memorandum to J. Karkoski, Central Valley RWQCB. Rancho Cordova, CA: Pesticide Investigation Unit, CA Department of Fish and Game
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
73306
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Three lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the criterion continuous concentration to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 0 samples exceed the criterion to protect human health from the consumption of water and organisms (California Toxics Rule) for MUN, and 0 of 6 samples exceed the California Toxics Rule criterion (inland surface waters) based on continuous concentration (30-day average) for freshwater for aquatic life protection (USEPA, 2000) for COMM.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of fifteen samples exceed the criterion continuous concentration to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 0 samples exceed the criterion to protect human health from the consumption of water and organisms (California Toxics Rule) for MUN, and 0 of 6 samples exceed the California Toxics Rule criterion (inland surface waters) based on continuous concentration (30-day average) for freshwater for aquatic life protection (USEPA, 2000) for COMM, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 73306, Dieldrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23275
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: - Six samples were collected from Willow Slough between November 2003 and September 2004. None of the Six samples exceeded the CTR criteria limit of 0.00014 ug/L for dieldrin (inland surface waters) based on continuous concentration (30-day average) for freshwater for aquatic life protection.- Three of the Six samples had a high Reporting Limit hence the data could not be used in the analysis for exceedance (Listing Policy, Section 6.5.1.1) (SWRCB, 2004).
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: California Toxics Rule criterion of 0.00014 ug/L for dieldrin (inland surface waters) based on continuous concentration (30-day average) for freshwater for aquatic life protection (USEPA, 2000).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected from an input channel of Willow Slough Bypass in Yolo County, California.
Temporal Representation: Samples were collected between November 2003 and September 2004 at irregular intervals.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 73306, Dieldrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72326
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dieldrin. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The criterion for Dieldrin to protect human health from the consumption of water and organisms is 0.00014 ug/L (California Toxics Rule).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 73306, Dieldrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72327
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Dieldrin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91014
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Disulfoton
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 19 samples exceed the Evaluation Guideline.

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

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. Zero of 19 samples exceeded the Evaluation Guideline and this does not exceed 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 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 91014, Disulfoton
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72355
 
Pollutant: Disulfoton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 19 samples exceed the criterion for Disulfoton.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The USEPA National Recommended Water Quality criterion for disulfoton in freshwater (0.05 ug/L) is an aquatic life maximum (instantaneous) level.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87148
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Endosulfan sulfate
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)(2016)
Revision Status Original
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 3.1a one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 15 samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 15 samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 87148, Endosulfan sulfate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72357
 
Pollutant: Endosulfan sulfate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endosulfan sulfate.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endosulfan Sulfate criterion for the protection of human health from consumption of water and organisms is 110 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91015
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000), for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from the consumption of water and organisms (CTR, 2000) for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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 .Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000), for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from the consumption of water and organisms (CTR, 2000) for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91015, Endrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72358
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endrin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endrin criterion for the protection of human health from the consumption of water and organisms is 0.76 ug/L. (California Toxics Rule, 2000)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91015, Endrin
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72359
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endrin.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L. (California Toxics Rule, 2000)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91016
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Endrin aldehyde
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 15 samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 15 samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91016, Endrin aldehyde
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72360
 
Pollutant: Endrin aldehyde
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endrin Aldehyde.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91072
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Heptachlor
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. There are no exceedances of the water quality objectives. Zero of zero samples exceed each of the COLD and MUN water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. There are no exceedances of the water quality objectives. Zero of zero samples exceed each of the COLD and MUN water quality objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91072, Heptachlor
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72418
 
Pollutant: Heptachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The CTR objective for Heptachlor to protect human health from the consumption of water and organisms is 0.00021 ug/L.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91072, Heptachlor
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72419
 
Pollutant: Heptachlor
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Heptachlor criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91073
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Heptachlor epoxide
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of zero samples exceed water quality objectives for neither COLD nor COMM.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceed water quality objectives for neither COLD nor COMM and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91073, Heptachlor epoxide
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72421
 
Pollutant: Heptachlor epoxide
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor epoxide. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Heptachlor Epoxide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91073, Heptachlor epoxide
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72420
 
Pollutant: Heptachlor epoxide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor epoxide. Fifteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The CTR objective for Heptachlor epoxide to protect human health from the consumption of water and organisms is 0.0001 ug/L.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87149
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Criteria/Objective.

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

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. Zero of 16 samples exceeded the Criteria/Objective and this does not exceed 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 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 87149, Lead
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72422
 
Pollutant: Lead
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Lead.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91074
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the criterion maximum concentration to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 15 samples exceed the California Primary MCL for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of fifteen samples exceed the criterion maximum concentration to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 15 samples exceed the California Primary MCL for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91074, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72447
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for HCH, gamma.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for HCH, gamma (Lindane) is 0.2 ug/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91074, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72448
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for HCH, gamma.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The gamma-HCH (Lindane) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87151
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Methomyl
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Evaluation Guideline.

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

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. Zero of 16 samples exceeded the Evaluation Guideline and this does not exceed 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 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 87151, Methomyl
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72480
 
Pollutant: Methomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceed the criterion for Methomyl.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Basin Plan states: "Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide..." The criteria continuous concentration for Methomyl is 0.5 ug/L (4-day average). (CDFG, 1996)
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91136
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Methoxychlor
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the narrative water quality objective for COLD, and 0 of 15 samples exceed the California Primary MCL for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of fifteen samples exceed the narrative water quality objective for COLD, and 0 of 15 samples exceed the California Primary MCL for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91136, Methoxychlor
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72481
 
Pollutant: Methoxychlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Methoxychlor.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for Methoxychlor, 30 ug/L, is incorporated by reference into the (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91136, Methoxychlor
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72482
 
Pollutant: Methoxychlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Methoxychlor.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91137
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 19 samples exceed the Evaluation Guideline.

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

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. Zero of 19 samples exceeded the Evaluation Guideline and this does not exceed 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 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 91137, Methyl Parathion
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72483
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 19 samples exceed the criterion for Parathion, Methyl.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The California Department of Fish and Game instantaneous aquatic life criterion for Methyl Parathion is 0.08 ug/L.
Guideline Reference: Hazard Assessment of the Insecticide Methyl Parathion to Aquatic Organisms in the Sacramento River System. California Department of Fish and Game. Environmental Services Division. Administrative Report 92-1
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91193
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Mirex
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 15 samples exceed the Evaluation Guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 15 samples exceeded Evaluation Guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91193, Mirex
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79539
 
Pollutant: Mirex
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Mirex.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The criterion continuous concentration for Mirex is 0.001 ug/l from the National Recommended Water Quality Criteria.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
91195
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Monuron
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Evaluation Guideline.

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

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. Zero of 16 samples exceeded the Evaluation Guideline and this does not exceed 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 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 91195, Monuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79540
 
Pollutant: Monuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Monuron.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The evaluation guideline for monuron, 330 ug/L, is one-tenth of the median lethal concentration (LC50).  The 1/10 LC50 for monuron is 330 ug/L (USEPA Office of Pesticide Programs Ecotoxicity database).
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
91196
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: N-(4-Chlorophenyl) -N' methylurea / Monuron
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Evaluation Guideline.

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

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. Zero of 16 samples exceeded the Evaluation Guideline and this does not exceed 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 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 91196, N-(4-Chlorophenyl) -N' methylurea / Monuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72517
 
Pollutant: N-(4-Chlorophenyl) -N' methylurea / Monuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Monuron.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Basin Plan states: "Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide..." The evaluation guideline for monuron, 330 ug/L, is one-tenth of the median lethal concentration (LC50 = 3,300 ug/L) for Lepomis gibbosus (Pumpkinseed sunfish). (USEPA Office of Pesticide Programs Ecotoxicity database)
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
95302
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of sixteen samples exceed the water quality objective for COLD, and 0 of 16 samples exceed the objective for MUN.

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

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. Zero of sixteen samples exceed the water quality objective for COLD, and 0 of 16 samples exceed the objective for MUN and this does not exceed 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 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 95302, Nickel
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72519
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Nickel.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 95302, Nickel
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72518
 
Pollutant: Nickel
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Nickel.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for nickel is 0.1 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87202
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Nitrate/Nitrite (Nitrite + Nitrate as N)
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)(2016)
Revision Status Original
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 3.1a one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the eight samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of eight samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 87202, Nitrate/Nitrite (Nitrite + Nitrate as N)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72551
 
Pollutant: Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 8 samples exceed the criterion for Nitrate/Nitrite as N.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for nitrate + nitrite (as N) is 10.0 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at Pole Line - 511XWLSPL]
Temporal Representation: Data was collected over the time period 2/16/2009-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87203
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Nitrogen, Nitrate
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Criteria/Objective.

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

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. Zero of 16 samples exceeded the Criteria/Objective and this does not exceed 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 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 87203, Nitrogen, Nitrate
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72552
 
Pollutant: Nitrogen, Nitrate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Nitrate as N.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for nitrate (NO3 as N) is 10.0 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-1/26/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91252
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Nitrogen, Nitrite
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 17 samples exceed the Criteria/Objective.

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

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. Zero of 17 samples exceeded the Criteria/Objective and this does not exceed 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 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 91252, Nitrogen, Nitrite
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72553
 
Pollutant: Nitrogen, Nitrite
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 17
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Nitrite as N.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for nitrite (as N) is 1 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-1/26/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91253
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Oxamyl (Vydate)
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)(2016)
Revision Status Original
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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 16 samples exceed the Criteria/Objective.

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

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. Zero of 16 samples exceeded the Criteria/Objective and this does not exceed 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 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 91253, Oxamyl (Vydate)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79541
 
Pollutant: Oxamyl (Vydate)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Oxamyl.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Maximum Contaminant Level for Oxamyl incorporated by reference in the Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins is 50 ug/L (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
91254
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Oxygen, Dissolved
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)(2016)
Revision Status Original
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 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 26 samples exceed the Criteria/Objective.

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

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. Zero of 26 samples exceeded the Criteria/Objective and this does not exceed the allowable frequency listed in Table 3.2 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 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 91254, Oxygen, Dissolved
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72556
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 26
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data to determine beneficial use support: None of 26 sample results exceed the criterion for Oxygen, Dissolved.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence was collected at two monitoring sites [Willow Slough Bypass at Pole Line-511XWLSPL and Willow Slough Bypass at SP-511XWLSBP].
Temporal Representation: Data was collected monthly between 2/10/2007 and 9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91255
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: 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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the zero samples exceed the Evaluation Guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceeded Evaluation Guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91255, Parathion
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72578
 
Pollutant: Parathion
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Parathion, Ethyl. Eighteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The USEPA national ambient water quality chronic criterion (4-hour maximum) for parathion, is 0.013 µg/L, is for freshwater aquatic life.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87253
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Silver
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)(2016)
Revision Status Original
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 3.1a two line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of three samples exceed the CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 3 samples exceed the California Secondary MCL for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of three samples exceed the CTR criterion continuous concentrations (4-day average) to protect aquatic life in freshwater for COLD, and 0 of 3 samples exceed the California Secondary MCL for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 87253, Silver
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72627
 
Pollutant: Silver
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Silver.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California secondary maximum contaminant level for silver is 0.1 mg/L.
Objective/Criterion Reference: Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 87253, Silver
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72628
 
Pollutant: Silver
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
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 agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Silver.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91379
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Temperature, water
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)(2016)
Revision Status Original
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: 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 satisfy the data quality requirements of section 6.1.4 of the Listing Policy.

2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Listing Policy. To determine the appropriate use support rating for COLD, an evaluation guideline identifying the optimal temperature range for rainbow trout for growth and completion of most life stages was used to interpret the narrative water quality objective for temperature. Section 6.1.5.2 of the Listing Policy states ¿¿samples should represent statistically or in a targeted manner the segment of the water body.¿ Water temperature data collected for this water body do not capture the spatial variability of temperatures experienced by aquatic life. Section 6.1.5.3 of the Listing Policy states ¿Samples should be representative of the critical timing that the pollutant is expected to impact the water body.¿ Water temperature data collected for this water body do not capture the temporal variability of temperatures experienced by aquatic life. Per Section 6.1.5.9 of the Listing Policy, ¿¿temperature monitoring data shall be compared to the temperature requirements of aquatic life living in the water segment.¿

Currently, the readily available data for water temperature in this segment are insufficient to determine whether growth and all life stages of rainbow trout are being supported. The monitoring program that generated the temperature data was not designed to evaluate attainment of temperature standards to support aquatic life. The surface water grab samples collected do not provide sufficient temporal and spatial representation of temperature conditions throughout the water body segment for fish exposure.

3. 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 91379, Temperature, water
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72650
 
Pollutant: Temperature, water
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 26
Number of Exceedances: 15
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 15 of 26 samples exceed the criterion for Water Temperature.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses (Sacramento-San Juoaquin River Basin Plans).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).
Guideline Reference: Inland Fishes of California (1976)
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87303
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Thallium
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)(2016)
Revision Status Original
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 two line(s) of evidence are necessary to assess listing status.

Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the three samples exceed the COLD water evaluation guideline, zero of the three samples exceed each of the COM and MUN water quality objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of three samples exceed the COLD water evaluation guideline, zero of three samples exceed each of the COM and MUN water quality objective, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 87303, Thallium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79145
 
Pollutant: Thallium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Thallium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Maximum Contaminant Level for thallium incorporated by reference in the Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins is 0.002 mg/L (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 87303, Thallium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79144
 
Pollutant: Thallium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Thallium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Thallium criteria for the protection of human health from consumption of organisms only is 6,300 mg/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 87303, Thallium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79143
 
Pollutant: Thallium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
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: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 3 samples exceed the criterion for Thallium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: 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. (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Gold Book states that thallium chronic toxicity to one species of fish occurs at concentrations as low as 20 ug/L after 2,600 hours of exposure.
Guideline Reference: Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [ Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 4/17/2007-6/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
91436
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Thiobencarb/Bolero
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the seven samples exceed the COLD water quality objective, zero of the seven samples exceed the MUN water evaluation guideline.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of seven samples exceed the COLD water quality objective, zero of seven samples exceed the MUN water evaluation guideline, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91436, Thiobencarb/Bolero
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72651
 
Pollutant: Thiobencarb/Bolero
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceed the criterion for Thiobencarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Basin Plan states: "Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide..." The evaluation guideline for Thiobencarb, 1.4 ug/L, is a maximum acceptable toxicicant concentration (MATC) calculated for Daphnia magna (Water flea). (USEPA Office of Pesticide Programs Ecotoxicity database)
Guideline Reference: OPP Pesticide Ecotoxicity Database.
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-12/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91436, Thiobencarb/Bolero
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72652
 
Pollutant: Thiobencarb/Bolero
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 7 samples exceed the criterion for Thiobencarb.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of Thiobencarb in excess of 1.0 µg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 1 monitoring site [Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-12/19/2007.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91437
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Toxaphene
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of zero samples exceed neither the COLD nor the MUN water quality objectives.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceed neither the COLD nor the MUN water quality objectives and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 91437, Toxaphene
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72676
 
Pollutant: Toxaphene
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: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Toxaphene. Fourteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Toxaphene criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0002 ug/L. (California Toxics Rule, 2000)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-8/18/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 91437, Toxaphene
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72675
 
Pollutant: Toxaphene
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Toxaphene. Fourteen samples were not used 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.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Toxaphene criterion for the protection of human health from the consumption of water and organisms is 0.00073 ug/L. (California Toxics Rule, 2000)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-8/18/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
87305
Region 5     
Willow Slough Bypass (Yolo County)
 
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)(2016)
Revision Status Original
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.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 16 samples exceed each of the COLD and MUN water quality objectives.

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

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. Zero of 16 samples exceeded each of the COLD and MUN water quality objectives and this does not exceed 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 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 87305, Zinc
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72678
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Zinc.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California secondary maximum contaminant level for zinc is 5.0 mg/L.
Objective/Criterion Reference: Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 87305, Zinc
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72679
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Zinc.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
100360
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from consumption of water and organisms (CTR, 2000) for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (CTR, 2000) for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from consumption of water and organisms (CTR, 2000) for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 100360, alpha-Endosulfan (Endosulfan 1)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72646
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endosulfan I.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endosulfan I criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 100360, alpha-Endosulfan (Endosulfan 1)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72645
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endosulfan I.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endosulfan I criterion for the protection of human health from consumption of water and organisms is 110 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90844
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: alpha.-BHC (Benzenehexachloride or alpha-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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the zero samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of zero samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90844, alpha.-BHC (Benzenehexachloride or alpha-HCH)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72644
 
Pollutant: alpha.-BHC (Benzenehexachloride or alpha-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
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 Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for HCH, alpha.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The HCH, alpha criterion, 0.0039 ug/L, is for the protection of human health from the consumption of water and organisms. (California Toxics Rule, 2002)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90900
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: beta-BHC (Benzenehexachloride or beta-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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 15 samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of 15 samples exceeded Criteria/Objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90900, beta-BHC (Benzenehexachloride or beta-HCH)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72696
 
Pollutant: beta-BHC (Benzenehexachloride or beta-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for HCH, beta.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The HCH, beta criterion for the protection of human health from the consumption of water and organisms is 0.014 ug/L (California Toxics Rule, 2002).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
90901
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: beta-Endosulfan (Endosulfan 2)
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)(2016)
Revision Status Original
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 one line(s) of evidence are necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from consumption of water and organisms (CTR, 2000) for MUN.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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. Zero of fifteen samples exceed the criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater (California Toxics Rule, 2000) for COLD, and 0 of 15 samples exceed the criterion for the protection of human health from consumption of water and organisms (CTR, 2000) for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
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 90901, beta-Endosulfan (Endosulfan 2)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72697
 
Pollutant: beta-Endosulfan (Endosulfan 2)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endosulfan II.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The beta-endosulfan criterion for the protection of human health from consumption of water and organisms is 110 ug/L. (California Toxics Rule, 2000)
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 90901, beta-Endosulfan (Endosulfan 2)
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72698
 
Pollutant: beta-Endosulfan (Endosulfan 2)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 15
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agvaiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Endosulfan II.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Endosulfan II criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91314
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: pH
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)(2016)
Revision Status Original
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 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Two of the 26 samples exceed the Criteria/Objective.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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 26 samples exceed the Criteria/Objective and this does not exceed the allowable frequency listed in Table 3.2 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 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 91314, pH
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 79142
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 26
Number of Exceedances: 2
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: State Water Board staff assessed ILRP data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 2 of 26 samples exceed the criterion for pH.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [ Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed
QAPP Information Reference(s):
 
 
DECISION ID
71817
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Selenium
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2016)
Revision Status Original
Sources: A Source Unknown
Expected TMDL Completion Date: 2027
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 one line(s) of evidence are necessary to assess listing status.

Three lines of evidence are available in the administrative record to assess this pollutant. Two of 16 water samples exceed the COLD objective, zero of six water samples exceed the WARM evaluation guideline, and zero of the 16 samples exceed the MUN objective,

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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 16 water samples exceed the COLD objective, and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. Zero of the 16 water samples exceed the MUN objective, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. Zero of 6 water samples exceed the WARM evaluation guideline, this does not exceed 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 71817, Selenium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72626
 
Pollutant: Selenium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 16
Number of Exceedances: 2
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 2 of 16 samples exceed the criterion for Selenium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.005 mg/L (California Toxics Rule, 2000).
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 71817, Selenium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 23283
 
Pollutant: Selenium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life 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 samples were collected on 6 occasions and analyzed for total recoverable and dissolved Se. The range of concentrations in total recoverable samples was 2-5 ?g/L. The concentrations in the April total recoverable sample equaled the CTR criterion. The range of concentrations in dissolved samples was 2-4??g/L.
Data Reference: Yolo Bypass Water Quality Management Plan Report. Prepared under CALFED Watershed Grant, Agreement # 4600001691 for the City of Woodland
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: CTR criterion of 5 ug/L, total recoverable Se, for the protection of freshwater aquatic life (4-day average concentration to protect from extended period of exposure).
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
Objective/Criterion Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Evaluation Guideline: The CTR criterion is expressed as total recoverable Se (USEPA, 2000). Because this dataset reported that most of the selenium in the samples was dissolved (i.e., was detected in the filtered fraction), the data for dissolved samples were also compared with the criterion.
Guideline Reference: Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
 
Spatial Representation: Samples were collected from an input channel of Willow Slough Bypass in Yolo County, California.
Temporal Representation: Samples were collected on: 11/22/03, 1/23/04, 4/23/04, 6/26/04, 8/20/04, and 9/22/04.
Environmental Conditions:
QAPP Information: Data quality: Good. Monitoring was conducted in accordance with the Quality Assurance Project Plan For Water Quality Monitoring For The Yolo Bypass Watershed Planning Project, 2003-2004
QAPP Information Reference(s):
 
Line of Evidence (LOE) for Decision ID 71817, Selenium
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72625
 
Pollutant: Selenium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 16
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 0 of 16 samples exceed the criterion for Selenium.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California primary maximum contaminant level for selenium is 0.05 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/15/2008.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
91378
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Specific Conductivity
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2016)
Revision Status Original
Sources: A Source Unknown
Expected TMDL Completion Date: 2027
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 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. 11 of the 26 samples exceed the water quality objective.

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. 11 of 26 samples exceed the water quality objectives and this exceeds the allowable frequency listed in Table 3.2 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 91378, Specific Conductivity
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72356
 
Pollutant: Specific Conductivity
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 26
Number of Exceedances: 11
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 11 of 26 samples exceed the criterion for Conductivity(Us).
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The California secondary maximum contaminant levels for electrical conductivity provide a range of values including a recommended level (900 uS/cm), an upper level (1,600 uS/cm) and a short-term level (2,200 uS/cm). The recommended level of 900 uS/cm was used as it is protective of all drinking water uses.
Objective/Criterion Reference: Secondary Maximum Contaminant Levels and Compliance. CCR Title 22 section 64449.
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
95394
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Toxicity
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2016)
Revision Status Original
Sources: A Source Unknown
Expected TMDL Completion Date: 2027
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 and 3.6 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

Two lines of evidence are available in the administrative record to assess this pollutant. Four of 22 water samples exhibited significant toxicity. The toxicity tests included survival of Ceriodaphnia dubia, total cell count of Selenastrum capricornutum and survival of Pimephales promelas. Zero of four sediment samples exhibited significant 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. Four of 22 water samples exhibited significant 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 95394, Toxicity
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 59210
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
Number of Exceedances: 4
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: Twenty-two samples were collected to evaluate water toxicity. Four of the samples exhibited significant toxicity. The toxicity tests included survival of Ceriodaphnia dubia, total cell count of Selenastrum capricornutum and survival of Pimephales promelas. 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: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-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 5 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
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. This data set reports a simple pass/fail (Yes/No) code to report toxicity that is equivalent to the SWAMP SL code.
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 Willow Slough Bypass at Pole Line and Willow Slough Bypass at SP.
Temporal Representation: The samples were collected from April 2007 to January 2008.
Environmental Conditions:
QAPP Information: Quality Assurance Project Plan Guidelines For Order NO. R5-2009-0875 Sacramento Valley Water Quality Coalition Monitoring And Reporting Program.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
Line of Evidence (LOE) for Decision ID 95394, Toxicity
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 59211
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: Four samples were collected to evaluate sediment toxicity. None of the samples exhibited significant toxicity. The toxicity tests included survival 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: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-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 5 Basin Plan.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
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 using the significant effect code: S equals significant, SG equals significantly greater and SL equals significantly lower. If a sample has any one of these codes, it will be considered an exceedance.
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 samples were collected at Willow Slough Bypass at Pole Line and Willow Slough Bypass at SP.
Temporal Representation: The samples were collected in from April and August 2007 and April and August 2008.
Environmental Conditions:
QAPP Information: Quality Assurance Project Plan Guidelines For Order NO. R5-2009-0875 Sacramento Valley Water Quality Coalition Monitoring And Reporting Program.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
95917
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Chlorpyrifos
Final Listing Decision: List on 303(d) list (being addressed by action other than TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (being addressed by action other than TMDL)(2016)
Revision Status Original
Sources: Agriculture
Expected Attainment Date: 2026
Implementation Action Other than TMDL: This water body segment-pollutant combination is being addressed through Basin Plan requirements established under CRWQCB-CVR resolution R5-20140041, and implemented through Board established Waste Discharge Requirements for agricultural discharges. The sources of chlorpyrifos to this segment have been identified as offsite movement of chlorpyrifos from chlorpyrifos applications by the agricultural dischargers regulated by the CRWQCB-CVR WDRs. The Basin Plan identifies numeric water quality objectives for diazinon and chlorpyrifos. The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for chlorpyrifos as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of chlorpyrifos into surface water. The Basin Plan and the Monitoring and Reporting programs in the WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are achieved.
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This water body - pollutant combination 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. One line of evidence is available in the administrative record to assess this pollutant. The evidence indicates that chlorpyrifos concentrations are not attaining the applicable water quality standards, but existing pollution control requirements, under State authority, are stringent enough to implement applicable water quality standards because the impairment is being addressed by an enforceable regulatory program, other than a TMDL, that is reasonably expected to result in attainment of the water quality standards within a reasonable, specified time frame.
This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Two of 19 available calculated 4-day average chlorpyrifos concentrations exceeded the 4-day average chlorpyrifos criterion. These exceedances occurred more than once every three years.
4. One of 19 available 1-hour average chlorpyrifos concentrations exceeded the 1-hour average chlorpyrifos criterion. This exceedance did not occur more than once every three years.
5. The sources of chlorpyrifos to this water body segment have been identified as offsite movement of chlorpyrifos from chlorpyrifos applications by the agricultural dischargers, who are regulated under enforceable Waste Discharge Requirements (WDRs).
6. In 2016, the Board adopted Resolution R5-2014-0041 establishing Basin Plan amendments that primarily address the regulation of agricultural pesticide runoff and discharges of diazinon and chlorpyrifos in the Central Valley which are implemented through Board established Waste Discharge Requirements for agricultural dischargers. The amendments established numeric water quality objectives for chlorpyrifos and a control program to ensure that the objectives will be attained within a reasonable, specified time frame.

The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for chlorpyrifos as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval.
7. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of chlorpyrifos into surface water.
8. The Basin Plan and the Monitoring and Reporting programs in the Boards WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are attained.
9. 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 described in the lines of evidence associated with this decision, the Regional Water Board determined that this water body and pollutant combination is impaired and that it should be listed as being addressed by another regulatory program that is reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame because an alternative State regulatory program is in place which can be reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame.
 
State Board Review of Regional Board Conclusion and Recommendation: The Basin Plan and WDRs require growers to implement management practices through the development and implementation of water quality management plans to meet water quality objectives for chlorpyrifos as soon as possible but no longer than ten years from the date of approval of the Basin Plan Amendment. These management plans are required to be developed and implemented within one year of the Basin Plan Amendment approval.
7. Agricultural management practices to be implemented may include pest management practices, pesticide application practices, vegetation management practices and water management practices, all of which are effective in reducing offsite movement of chlorpyrifos into surface water.
8. The Basin Plan and the Monitoring and Reporting programs in the Boards WDRs require monitoring to determine if adequate reductions are being attained. The Basin Plan and WDRs require management practices to be iteratively improved through updates of the management plans until the water quality objectives are attained.
9. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
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 95917, Chlorpyrifos
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 72271
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 2
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support and results are as follows: 2 of 19 samples exceed the criterion for Chlorpyrifos.
Data Reference: Data for Various Pollutants in Sacramento Valley Water Quality Coalition, 2005-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The freshwater criterion continuous concentration to protect aquatic organisms is 0.015 ug/L (Siepmann and Finlayson 2000).
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: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at 2 monitoring sites [Willow Slough Bypass at Pole Line - 511XWLSPL, Willow Slough Bypass at SP - 511XWLSBP]
Temporal Representation: Data was collected over the time period 2/10/2007-9/22/2009.
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: The Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition was followed.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
93837
Region 5     
Willow Slough Bypass (Yolo County)
 
Pollutant: Diuron
Final Listing Decision: List on 303(d) list (being addressed by action other than TMDL)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (being addressed by action other than TMDL)(2016)
Revision Status Original
Sources: Agriculture
Expected Attainment Date: 2020
Implementation Action Other than TMDL: This listing is being addressed through the implementation of the Central Valley Regional Water Quality Control Board Irrigated Lands Regulatory program (ILRP) Waste Discharge Requirements (WDRs) for Growers within the Sacramento River Watershed that are Members of the Third-Party Group (Order R5-2014-0030-R1, amended by orders R5-2015-0115, R5-2016-0014, and R5-2016-0015) and in Waste Discharge Requirements General Order for Discharges from Irrigated Lands within the Central Valley Region for Dischargers not Participating in a Third-party Group (Order R5-2013-0100). The sources of diuron to this waterbody segment have been identified as offsite movement of diuron from diuron applications by the agricultural dischargers regulated by the CRWQCB-CVR WDRs. The WDRs include a time schedule, milestones and a monitoring and reporting program. The WDRs require growers to develop and implement water quality management plans iteratively to attain water quality objectives as soon as possible, but no later than ten years from the identification of water quality exceedances. The WDRs monitoring and reporting program requires growers to regularly monitor water bodies with management plans to assess progress at meeting standards and regularly report monitoring results to the Regional Board. A management plan for diuron in Willow Slough Bypass was developed in 2010 and is being implemented and monitoring is ongoing. Agricultural management practices being used to reduce offsite movement of diuron into surface water include alternative weed management practices, pesticide application practices, vegetation management and water management practices, pesticide application practices, vegetation management and water management practices, all of which are effective in reducing offsite movement of diuron into surface water. The WDRs require management practices to be iteratively improved through updates of the management plans until water quality criteria are achieved. The diuron criteria are expected to be attained through continued implementation and improvement of management practices within the required 10-year compliance time frame.
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This water body pollutant combination 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. One line of evidence is available in the administrative record to assess this pollutant. The evidence indicates that diuron concentrations are not attaining the applicable water quality standards, but other pollution control requirements, under State authority, are stringent enough to implement applicable water quality standards.
Based on the readily available data and information, the weight of evidence indicates this water segment-pollutant combination is not meeting standards, but the impairment is being addressed by an enforceable regulatory program, other than a TMDL, that is reasonably expected to result in attainment of the water quality standards within a reasonable, specified time frame.
This conclusion is based on the staff findings that:
1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Six of 18 samples exceeded the water quality criterion and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. This listing is being addressed through the implementation of the Central Valley Regional Water Quality Control Board Irrigated Lands Regulatory program (ILRP) Waste Discharge Requirements (WDRs) for Growers within the Sacramento River Watershed that are Members of the Third-Party Group (Order R5-2014-0030-R1, amended by orders R5-2015-0115, R5-2016-0014, and R5-2016-0015) and in WDRs General Order for Discharges from Irrigated Lands within the Central Valley Region for Dischargers not Participating in a Third-party Group (Order R5-2013-0100).
The WDRs include a time schedule, milestones and a monitoring and reporting program. The WDRs require growers to develop and implement water quality management plans iteratively to attain water quality objectives as soon as possible, but no later than ten years from the identification of water quality exceedances. A management plan for diuron in Willow Slough Bypass was developed in 2010 and is being implemented and monitoring is ongoing. Agricultural management practices being used to reduce offsite movement of diuron into surface water include alternative weed management practices, pesticide application practices, vegetation management and water management practices. The diuron criteria are expected to be attained through continued implementation and improvement of management practices within the required 10-year compliance time frame.
5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are being met.
 
Regional Board Decision Recommendation: After review of the available data and information described in the lines of evidence associated with this decision, the Regional Water Board determined that this water body and pollutant combination is still impaired and that it should be listed as being addressed by another regulatory program that is reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame, because an alternative State regulatory program is in place which can be reasonably expected to result in attainment of the water quality standard within a reasonable, specified time frame.
 
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 93837, Diuron
Region 5     
Willow Slough Bypass (Yolo County)
 
LOE ID: 78610
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Cold Freshwater Habitat
Aquatic Life Use: Cold Freshwater Habitat
 
Number of Samples: 18
Number of Exceedances: 6
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Willow Slough Bypass (Yolo County) to determine beneficial use support. Six of the 18 sample results were detected at levels above Diuron criterion of 1.3 ug/L.
Data Reference: Data for Various Pollutants in Westside San Joaquin Water Quality Coalition, 2004-2009.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses.
Objective/Criterion Reference: Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition
 
Evaluation Guideline: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141. The acute exposure (4-day average) value for Diuron is 1.3 ug/L.
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: Data for this line of evidence for Willow Slough Bypass (Yolo County) was collected at two monitoring sites: [Willow Slough Bypass at SP - 511XWLSBP; Willow Slough Bypass at Pole Line - 511XWLSPL]
Temporal Representation: Data was collected monthly between 2/10/2007 and 9/15/2008
Environmental Conditions: Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.
QAPP Information Reference(s):