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

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name: Walker Creek (Glenn County)
Water Body ID: CAR5202100020101024220320
Water Body Type: River & Stream
 
DECISION ID
147300
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Toxicity
Final Listing Decision: Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
Reason for Delisting: Applicable WQS attained; reason for recovery unspecified
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.

Four lines of evidence are available in the administrative record to assess this pollutant. Three of 75 water samples exhibited significant toxicity. The toxicity tests included survival of Ceriodaphnia dubia, total cell count of Selenastrum capricornutum and survival of Pimephales promelas. One of 13 sediment samples tested with Hyalella azteca exhibited significant toxicity.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for 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. Three of 75 water samples exhibited significant toxicity. The toxicity tests included survival of Ceriodaphnia dubia, total cell count of Selenastrum capricornutum and survival of Pimephales promelas. One of 13 sediment samples tested with Hyalella azteca exhibited significant toxicity and this does not exceed 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 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 removed from the section 303(d) list because applicable water quality standards for the pollutant 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 147300, Toxicity
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 59209
 
Pollutant: Sediment Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: Six 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 Walker Creek at County Road 48 and Walker Creek near 99W and CR33.
Temporal Representation: The samples were collected in from April 2007 to August 2009.
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 147300, Toxicity
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 297099
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 48
Number of Exceedances: 0
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 0 of the 48 samples collected by Sacramento Valley Water Quality Coalition for Walker Creek (Glenn County) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Ceriodaphnia dubia for Survival, Selenastrum capricornutum for Total Cell Count, Pimephales promelas for Survival.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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. 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: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 520XWLKCH ( Walker Creek near 99W and CR33 ).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2019-09-26.
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147300, Toxicity
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 59208
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 27
Number of Exceedances: 3
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: Twenty-seven samples were collected to evaluate water toxicity. Three 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 Walker Creek at County Road 48 and Walker Creek near 99W and CR33.
Temporal Representation: The samples were collected from April 2007 to September 2009.
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 147300, Toxicity
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 297100
 
Pollutant: Toxicity
LOE Subgroup: Toxicity
Matrix: Sediment
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 1
 
Data and Information Type: TOXICITY TESTING
Data Used to Assess Water Quality: 1 of the 7 samples collected by Sacramento Valley Water Quality Coalition for Walker Creek (Glenn County) exhibited toxicity. A sample may have multiple toxicity test results, but will only be counted once. A sample is defined as being collected on the same day and the same location. The following organisms and parameters were utilized for the toxicity tests: Hyalella azteca for Survival. The following tests exhibited toxicity: Hyalella azteca for Survival on 2019-08-22.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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. 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: The sample is toxic when the response of the organisms exposed to the sample is significantly different (worse) than the response of the organisms exposed to the laboratory control based on statistical hypothesis testing.  An exceedance is counted when the significant effect code is “Significant; Less Similarity,” which means that the sample result is significantly different than the control result, and the percent effect is greater than the evaluation threshold.  The default evaluation threshold is 20% unless otherwise stated.
Guideline Reference: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. Fourth Edition. Office of Water, U.S. Environmental Protection Agency. Washington, D.C. EPA-821-R-02-013
 
Spatial Representation: The samples were collected at monitoring site: 520XWLKCH ( Walker Creek near 99W and CR33 ).
Temporal Representation: The samples were collected between the dates of 2011-04-21 and 2019-08-22.
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147265
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Chlorpyrifos
Final Listing Decision: Delist from 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)(2018)
Revision Status Revised
Reason for Delisting: Applicable WQS attained; reason for recovery unspecified
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 R5-2014-0041, 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 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.

Two lines of evidence is available in the administrative record to assess this pollutant. Three of 43 samples exceed the evaluation guideline for WARM.

Based on available data, there is sufficient justification for removing this segment from the 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 Policy.
2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Three of 43 samples exceed the evaluation guideline for WARM and this does not exceed the allowable frequency from Table 4.1 of the Listing Policy.
4. 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).
5. 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.
6. 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.
7. 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 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 be removed from the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded.
 
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.
6. 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.
7. 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 4.11 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 147265, Chlorpyrifos
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293517
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 20
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 20 samples exceeded the water quality threshold for Chlorpyrifos.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 freshwater criterion continuous concentration to protect aquatic organisms is 0.015 ug/L (Siepmann and Finlayson 2000, with minor corrections to significant figures as described in Beaulaurier et al., 2005).
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game (with minor corrections to significant figures as described in Beaulaurier et al., 2005).
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147265, Chlorpyrifos
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72101
 
Pollutant: Chlorpyrifos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 23
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 3 of 23 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
149414
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Indicator Bacteria
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
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.

The State Water Board’s Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California (the “ISWEBE Plan”) contains two bacteria water quality objectives applicable to the REC-1 beneficial use, which were adopted on August 7, 2018. Because the salinity level of this waterbody is equal to or less than 1 part per thousand 95 percent or more of the time, the E. coli bacteria objective applies Therefore, this waterbody is being considered for removal from the CWA section 303(d) List under section 4.3 of the Listing Policy using the E. coli objective.

A total of three lines of evidence of E. coli and fecal coliform data were evaluated for this waterbody. Of these lines of evidence, two are based on historic E. coli and fecal coliform data collected prior to 2010. One is based on recent E.coli data, collected since 2010, and compared to the newer E. coli bacteria water quality objective.

In accordance with section 6.1.5.3 of the Listing Policy, data should be representative of the critical timing that the pollutant is expected to impact the waterbody. Indicator bacteria (total coliform, fecal coliform, E. coli, enterococci) populations may fluctuate substantially on a daily, seasonal, or yearly basis. Lacking constant inputs, they do not persist in the environment for a long period and effects are of relatively short duration. As a result, the historic levels of indicator bacteria in the waterbody may be a poor indicator of current risks to human health, particularly when more recent data are available to sufficiently assess the water quality standard. Unrepresentative data may result in incorrectly placing or not placing a water body segment on the list, which could result in the unnecessary expenditure of public resources or missing a human health problem. The two historic lines of evidence were evaluated pursuant to these considerations and were not used to assess water quality standards attainment because they do not meet the temporal representation requirements of section 6.1.5.3 of the Listing Policy.

The one recent E. coli line of evidence was relied upon to assess water quality standards attainment in this waterbody. The data were collected from 2010-2018. There are adequate data to determine beneficial use support in accordance with the Listing Policy. The data are representative of existing conditions in the waterbody and represent a range of hydrologic conditions (both wet and dry years).

With respect to the recent lines of evidence, 26 of 59 STVs for E. coli calculated from 2010 to 2018 exceed the E. coli bacteria objective. For these data, Listing Policy section 4.3 instructs to use the binomial distribution table in section 4.2. Using this exceedance frequency, the number of exceedances is not sufficient to remove this waterbody from the list.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this waterbody from the list.

The data used satisfy 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 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 149414, Indicator Bacteria
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 301184
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: STV
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 59
Number of Exceedances: 26
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and the results are as follows: 26 of the 59 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a STATISTICAL THRESHOLD VALUE (STV) of 320 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly).
Objective/Criterion Reference: Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site(s), station(s): 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the days of 2010-09-23 and 2018-12-19 .
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 149414, Indicator Bacteria
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72131
 
Pollutant: Escherichia coli (E. coli)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 24
Number of Exceedances: 10
 
Data and Information Type: PATHOGEN MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 10 of 24 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 California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 149414, Indicator Bacteria
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72133
 
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 Walker Creek (Glenn 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 for the Sacramento River 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. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Data for this line of evidence for Walker Creek (Glenn County) was collected at 1 monitoring site [Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 4/22/2009-6/18/2009.
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
147293
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Oxygen, Dissolved
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2018)
Revision Status Revised
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.

Three lines of evidence are available in the administrative record to assess this pollutant. 22 of 101 samples exceed the objective for WARM. 20 of 73 samples exceed the objective for SPWN.

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. 22 of 101 samples exceed the objective for WARM. 20 of 73 samples exceed the objective for SPWN. 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 147293, Oxygen, Dissolved
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72209
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 28
Number of Exceedances: 12
 
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: 12 of 28 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 WARM is 5.0 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 five monitoring sites [Walker Creek at County Road 48-520XWLKRC (16 averaged sample results), Walker Creek at Road 46 Bridge FU-520XWLKFU (1 sample result), Walker Creek below Artois-520XWLKBA (1 sample result), Walker Creek near 99W and CR33-520XWLKCH (9 averaged sample results) and Walker Creek Rd 33 between I5 and 99-520XWLK33 (1 sample result)].
Temporal Representation: Data was collected monthly during summer months between 5/16/2007 and 9/23/2009.
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 147293, Oxygen, Dissolved
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295559
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 73
Number of Exceedances: 10
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 10 of 73 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2010-09-23 and 2020-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147293, Oxygen, Dissolved
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295412
 
Pollutant: Oxygen, Dissolved
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Fish Spawning
 
Number of Samples: 73
Number of Exceedances: 20
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 20 of 73 samples exceeded the water quality threshold for Oxygen, Dissolved.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The minimum dissolved oxygen concentration for waters designated as SPWN is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2010-09-23 and 2020-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147291
Region 5     
Walker Creek (Glenn County)
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147291, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294091
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 dichlorophenoxyacetic acid, 2,4- (2,4-D) is the USEPA Aquatic Life Benchmark of 299.2 ug/L for a vascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-06-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147291, 2,4-D (2,4-Dichlorophenoxy acetic acid)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294070
 
Pollutant: 2,4-D (2,4-Dichlorophenoxy acetic acid)
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Dichlorophenoxyacetic Acid, 2,4-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 USEPA recommended criterion for 2,4-D for the protection of human health from the consumption of organisms only is 1,300 ug/L .
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-06-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147259
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Acetamiprid
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 147259, Acetamiprid
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292827
 
Pollutant: Acetamiprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Acetamiprid.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 acetamiprid is the USEPA Aquatic Life Benchmark of 2.1 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-07-18 and 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147323
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147323, Aldicarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221541
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147323, Aldicarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292829
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Aldicarb.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147323, Aldicarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221449
 
Pollutant: Aldicarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 6 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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
147324
Region 5     
Walker Creek (Glenn 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)(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.

Three line of evidence is available in the administrative record to assess this pollutant. Zero of the 24 samples exceed the criteria for aquatic life.

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 24 samples exceed the criteria for aquatic life 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 147324, Aldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292819
 
Pollutant: Aldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Aldrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The aldrin criterion for the protection of human health from consumption of organisms only is 0.00014 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147324, Aldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292791
 
Pollutant: Aldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Aldrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The aldrin criterion maximum concentration (expressed as a 1-day average) to protect aquatic life in freshwater is 1.5 ug/L. The criterion of 3 ug/L provided in the California Toxics Rule is an instantaneous maximum concentration and was divided by 2 in order to better represent a criterion maximum concentration (CMC) value as specified in footnote (g) of Table (b)(1) of the California Toxics Rule (2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147324, Aldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72069
 
Pollutant: Aldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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
147255
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Allethrin
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 147255, Allethrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293066
 
Pollutant: Allethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Allethrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 allethrin is the USEPA Aquatic Life Benchmark of 1.05 ug/L for an invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
153941
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Aluminum
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 153941, Aluminum
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 314616
 
Pollutant: Aluminum
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Aluminum.
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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The aluminum criterion for the protection of aquatic life, is pH, total hardness, and dissolved organic carbon (DOC) dependent. When total hardness or DOC data were not available, default values based on the level III ecoregions developed by U.S EPA were substituted (EPA, 2018). When pH data were not available, the median pH value for the ecoregion, a pH value from a comparable waterbody, or a pH value from a local study in the same waterbody was used as a comparable surrogate.
Guideline Reference: Final Aquatic Life Ambient Water Quality Criteria for Aluminum. EPA-822-R-18-001. Washington, D.C.: Office of Water, USEPA.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKRC (Walker Creek at County Road 48).
Temporal Representation: The samples were collected between the dates of 2007-05-15 and 2007-05-15
Environmental Conditions:
QAPP Information: Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
QAPP Information Reference(s): Quality Assurance Project Plan for Sacramento Valley Water Quality Coalition.
 
 
DECISION ID
129053
Region 5     
Walker Creek (Glenn 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: 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 72072 has been replaced by LOE 221657 and LOE 221656 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 129053, Atrazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221656
 
Pollutant: Atrazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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 129053, Atrazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221657
 
Pollutant: Atrazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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
147280
Region 5     
Walker Creek (Glenn 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)(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 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 147280, Azinphos-methyl (Guthion)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72084
 
Pollutant: Azinphos-methyl (Guthion)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Azinphos methyl. Twenty two 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147280, Azinphos-methyl (Guthion)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292956
 
Pollutant: Azinphos-methyl (Guthion)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Azinphos Methyl. Although a total of 4 samples were collected, 4 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 USEPA National Recommended Water Quality Criteria for azinphos methyl for freshwater aquatic life protection is 0.01 ug/l (instantaneous maximum)
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-01-19 to 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147304
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147304, Benomyl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293040
 
Pollutant: Benomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Benomyl.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147304, Benomyl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72085
 
Pollutant: Benomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 22 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
147312
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Bifenthrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147312, Bifenthrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293584
 
Pollutant: Bifenthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for bifenthrin is 0.1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Bifenthrin
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147305
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147305, Bromacil
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221487
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 6 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147305, Bromacil
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221509
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147305, Bromacil
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293591
 
Pollutant: Bromacil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Bromacil.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147260
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Cadmium
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147260, Cadmium
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293387
 
Pollutant: Cadmium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Cadmium.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The dissolved cadmium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 2.2 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2014-04-16 and 2014-04-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147261
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147261, Carbaryl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72088
 
Pollutant: Carbaryl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 22 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147261, Carbaryl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293450
 
Pollutant: Carbaryl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Carbaryl.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 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. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147262
Region 5     
Walker Creek (Glenn 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)(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 is available in the administrative record to assess this pollutant. Zero of the 37 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 37 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: This decision was made by SWRCB staff.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the following changes to the decision:
The water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147262, Carbofuran
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72100
 
Pollutant: Carbofuran
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 22 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147262, Carbofuran
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 307383
 
Pollutant: Carbofuran
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Carbofuran.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 interim water quality criterion for the protection of sensitive aquatic organisms from Carbofuran is 0.5 ug/l (DFG 92-3, 1992).
Guideline Reference: Hazard Assessment of the Insecticide Carbofuran to Aquatic Organisms in the Sacramento River System
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147263
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Chlordane
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147263, Chlordane
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296791
 
Pollutant: Chlordane
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Total Chlordane. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The chlordane criterion for the protection of human health from consumption of organisms only is 0.00059 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147263, Chlordane
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296935
 
Pollutant: Chlordane
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Total Chlordane. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chlordane criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0043 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147342
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Chloropicrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147342, Chloropicrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293393
 
Pollutant: Chloropicrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chloropicrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 chloropicrin is the USEPA Aquatic Life Benchmark of 5.5 ug/L for a fish (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-10-17 to 2018-10-17
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147264
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Chlorothalonil
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147264, Chlorothalonil
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293432
 
Pollutant: Chlorothalonil
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Chlorothalonil.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 chlorothalonil is the USEPA Aquatic Life Benchmark of 0.6 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147266
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Copper
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147266, Copper
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293525
 
Pollutant: Copper
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Copper.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The dissolved copper criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 9 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2018-05-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147330
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Cyfluthrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147330, Cyfluthrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293884
 
Pollutant: Cyfluthrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for cyfluthrin is 0.2 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cyfluthrin
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147332
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Cyhalothrin, Lambda
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147332, Cyhalothrin, Lambda
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294745
 
Pollutant: Cyhalothrin, Lambda
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. Although a total of 4 samples were collected, 4 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of Lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Lambda-cyhalothrin
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147313
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Cypermethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147313, Cypermethrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293871
 
Pollutant: Cypermethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for cypermethrin is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of Cypermethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Cypermethrin
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
150239
Region 5     
Walker Creek (Glenn County)
 
Pollutant: DDD (Dichlorodiphenyldichloroethane)
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 150239, DDD (Dichlorodiphenyldichloroethane)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293759
 
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: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDD(p,p'). Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The 4,4'-DDD criterion for the protection of human health from consumption of organisms only is 0.00084 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
150259
Region 5     
Walker Creek (Glenn County)
 
Pollutant: DDE (Dichlorodiphenyldichloroethylene)
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 150259, DDE (Dichlorodiphenyldichloroethylene)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293879
 
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: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDE(p,p'). Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The 4,4'-DDE [DDE(p,p')] criterion to protect human health from the consumption of organisms only is 0.00059 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
150231
Region 5     
Walker Creek (Glenn 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)(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.

Three lines of evidence are available in the administrative record to assess this pollutant. One of the 19 samples exceed the criteria for WARM.

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 19 samples exceed the criteria 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: 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 150231, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293725
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The DDT(4,4') 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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 150231, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72103
 
Pollutant: DDT (Dichlorodiphenyltrichloroethane)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 19
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed agwaiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 1 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected monthly between 2/8/2007 and 5/20/2009. One pair of samples was 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 150231, DDT (Dichlorodiphenyltrichloroethane)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293783
 
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: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The DDT(4,4') criterion for the protection of human health from consumption of organisms only is 0.00059 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147267
Region 5     
Walker Creek (Glenn 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)(2020)
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: This decision was made by SWRCB staff.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147267, Dacthal
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293681
 
Pollutant: Dacthal
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Dacthal.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147267, Dacthal
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221629
 
Pollutant: Dacthal
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-04-17 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.
 
Line of Evidence (LOE) for Decision ID 147267, Dacthal
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221651
 
Pollutant: Dacthal
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 4 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-05-20
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
147331
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Deltamethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147331, Deltamethrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293864
 
Pollutant: Deltamethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Deltamethrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 deltamethrin is the USEPA Aquatic Life Benchmark of 0.000026 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147334
Region 5     
Walker Creek (Glenn 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)(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 33 samples exceed the Evaluation Guideline for WARM.

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 33 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: 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 147334, Demeton
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72104
 
Pollutant: Demeton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 17 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147334, Demeton
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293609
 
Pollutant: Demeton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Demeton, Total.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 USEPA National Recommended Water Quality criterion for demeton for freshwater aquatic life protection is 0.1 ug/l (4 day average)
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147269
Region 5     
Walker Creek (Glenn 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)(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.

The number of measured exceedances is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicant pollutants (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 this water segment-pollutant combination should not be placed on the CWA section 303(d) List.

Refer to the lines of evidence in this fact sheet for the data and information, sample counts and exceedances, quality assurance documentation, beneficial uses, and water quality objectives or numeric evaluation guidelines relied upon for this decision.
 
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 147269, Diazinon
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293849
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 20
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 20 samples exceeded the water quality threshold for Diazinon.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 freshwater chronic value for diazinon is 0.10 ug/L (4 day average)(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
Guideline Reference: Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game (with minor corrections to significant figures as described in Beaulaurier et al., 2005).
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147269, Diazinon
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72114
 
Pollutant: Diazinon
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 23
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 23 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
147270
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Dichlorvos
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147270, Dichlorvos
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294243
 
Pollutant: Dichlorvos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Dichlorvos. Although a total of 20 samples were collected, 20 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 dichlorvos is the USEPA Aquatic Life Benchmark of 0.0058 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-01-19 to 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147271
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147271, Dicofol
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221706
 
Pollutant: Dicofol
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147271, Dicofol
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221659
 
Pollutant: Dicofol
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 4 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-05-20
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 147271, Dicofol
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294267
 
Pollutant: Dicofol
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Dicofol.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147272
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147272, Dieldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72116
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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 147272, Dieldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293917
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Dieldrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147272, Dieldrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294249
 
Pollutant: Dieldrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Dieldrin. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The dieldrin criterion for the protection of human health from consumption of organisms only is 0.00014 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147343
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Diflubenzuron
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 147343, Diflubenzuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294117
 
Pollutant: Diflubenzuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Diflubenzuron. Although a total of 17 samples were collected, 16 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 diflubenzuron is the USEPA Aquatic Life Benchmark of 0.00025 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (520XWLKCH).
Temporal Representation: Data for this waterbody was collected over the date range 2011-01-19 to 2017-10-25
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147315
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147315, Dimethoate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221576
 
Pollutant: Dimethoate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147315, Dimethoate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221624
 
Pollutant: Dimethoate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147315, Dimethoate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294185
 
Pollutant: Dimethoate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Dimethoate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2013-03-21 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147273
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147273, Disulfoton
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294168
 
Pollutant: Disulfoton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Disulfoton.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 disulfoton is the USEPA Aquatic Life Benchmark of 0.01 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147273, Disulfoton
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72118
 
Pollutant: Disulfoton
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 23
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 23 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
147274
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Diuron
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.
 
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 147274, Diuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 78608
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 Walker Creek (Glenn County) to determine beneficial use support. None of the 22 sample results were above the 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 Walker Creek (Glenn County) was collected at two monitoring sites: [Walker Creek at County Road 48 - 520XWLKRC; Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected annually between 2/08/2007 and 9/23/2009
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):
 
Line of Evidence (LOE) for Decision ID 147274, Diuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294234
 
Pollutant: Diuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for Diuron.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2017-10-25
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147275
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Endosulfan sulfate
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 147275, Endosulfan sulfate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294372
 
Pollutant: Endosulfan sulfate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan Sulfate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The USEPA National Recommended Water Quality Criteria toxicity threshold for endosulfan sulfate for freshwater aquatic life protection is 0.056 ug/l (24 hour average)
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147275, Endosulfan sulfate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294298
 
Pollutant: Endosulfan sulfate
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan Sulfate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endosulfan sulfate criterion for the protection of human health from consumption of organisms only is 240 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147276
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147276, Endrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72130
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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 147276, Endrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294502
 
Pollutant: Endrin
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endrin criterion to protect human health from the consumption of organisms only is 0.81 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147276, Endrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294478
 
Pollutant: Endrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147277
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Endrin aldehyde
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 147277, Endrin aldehyde
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294281
 
Pollutant: Endrin aldehyde
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endrin Aldehyde.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endrin aldehyde criterion to protect human health from the consumption of organisms only is 0.81 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147335
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Esfenvalerate/Fenvalerate
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147335, Esfenvalerate/Fenvalerate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294397
 
Pollutant: Esfenvalerate/Fenvalerate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for esfenvalerate is 0.3 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of Esfenvalerate were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Esfenvalerate
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147317
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Ethalfluralin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147317, Ethalfluralin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294506
 
Pollutant: Ethalfluralin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Ethalfluralin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 Ethalfluralin is the USEPA Aquatic Life Benchmark of 0.4 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-06-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147318
Region 5     
Walker Creek (Glenn 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)(2020)
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 72132 has been replaced by LOE 221997 and LOE 221998 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. 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 147318, Ethoprop
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294556
 
Pollutant: Ethoprop
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 samples exceeded the water quality threshold for Ethoprop.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147318, Ethoprop
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221997
 
Pollutant: Ethoprop
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147318, Ethoprop
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221998
 
Pollutant: Ethoprop
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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
147333
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Fenpropathrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147333, Fenpropathrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294606
 
Pollutant: Fenpropathrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 4
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and the results are as follows: 0 of the 4 samples exceeded the water quality threshold for Fenpropathrin. Although a total of 5 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site (520XWLKCH).
Temporal Representation: Data for this waterbody was collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147326
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Fenthion
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy.

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:
 
 
Line of Evidence (LOE) for Decision ID 147326, Fenthion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294361
 
Pollutant: Fenthion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Fenthion.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 fenthion is the USEPA Aquatic Life Benchmark of 0.013 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147278
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Fluometuron
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 147278, Fluometuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294513
 
Pollutant: Fluometuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Fluometuron.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 floumeturon is the USEPA Aquatic Life Benchmark of 30 ug/L for nonvascular plants.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147279
Region 5     
Walker Creek (Glenn 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)(2020)
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 72134 has been replaced by LOEs 221792 and 221856 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 147279, Glyphosate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221856
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 7 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-08-19
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 147279, Glyphosate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294545
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Glyphosate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-07-18 and 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147279, Glyphosate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221792
 
Pollutant: Glyphosate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 12 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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
147281
Region 5     
Walker Creek (Glenn 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)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147281, Heptachlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294888
 
Pollutant: Heptachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147281, Heptachlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294792
 
Pollutant: Heptachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The heptachlor criterion to protect human health from the consumption of organisms only is 0.00021 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147281, Heptachlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72148
 
Pollutant: Heptachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor.
Nineteen 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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
147282
Region 5     
Walker Creek (Glenn 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)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147282, Heptachlor epoxide
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294736
 
Pollutant: Heptachlor epoxide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The heptachlor epoxide criterion for the protection of human health from consumption of organisms only is 0.00011 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147282, Heptachlor epoxide
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294629
 
Pollutant: Heptachlor epoxide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147282, Heptachlor epoxide
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72149
 
Pollutant: Heptachlor epoxide
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Heptachlor epoxide. Nineteen 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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
147283
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Hexachlorobenzene/ HCB
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147283, Hexachlorobenzene/ HCB
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294873
 
Pollutant: Hexachlorobenzene/ HCB
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Hexachlorobenzene. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The hexachlorobenzene criterion for the protection of human health from consumption of organisms only is 0.00077 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-03-16 to 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147329
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Hexachlorocyclohexane (HCH), alpha
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 147329, Hexachlorocyclohexane (HCH), alpha
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294364
 
Pollutant: Hexachlorocyclohexane (HCH), alpha
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for HCH, alpha-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The alpha-HCH (alpha-BHC) criterion for the protection of human health from consumption of organisms only is 0.013 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147328
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Hexachlorocyclohexane (HCH), beta
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 147328, Hexachlorocyclohexane (HCH), beta
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294519
 
Pollutant: Hexachlorocyclohexane (HCH), beta
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for HCH, beta-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The beta-HCH (beta-BHC) criterion for the protection of human health from consumption of organisms only is 0.046 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147336
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Hexazinone
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147336, Hexazinone
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294743
 
Pollutant: Hexazinone
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Hexazinone.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 hexazinone is the USEPA Aquatic Life Benchmark of 7 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147306
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Imidacloprid
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation:
 
 
Line of Evidence (LOE) for Decision ID 147306, Imidacloprid
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294781
 
Pollutant: Imidacloprid
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Imidacloprid.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.
Guideline Reference: Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-06-20 and 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147284
Region 5     
Walker Creek (Glenn 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)(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.

Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the 24 samples exceed the Criteria/Objective for WARM and zero of five samples exceed the criteria 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 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 24 samples exceed the Criteria/Objective for WARM and zero of five samples exceed the criteria for COMM 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 147284, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72150
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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 147284, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294733
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for HCH, gamma-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The gamma-BHC (Lindane, gamma-HCH) criterion for the protection of human health from the consumption of organisms only is 0.063 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147284, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294711
 
Pollutant: Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for HCH, gamma-.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The gamma-BHC (Lindane, gamma-HCH) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L. (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147285
Region 5     
Walker Creek (Glenn 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)(2020)
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 72151 has been replaced by LOE 222049 and LOE 221771 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 147285, Linuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222049
 
Pollutant: Linuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn 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 6 samples were collected, 6 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 (520XWLKCH).
Temporal Representation: Date for this waterbody was collected over the date range 2009-02-19 to 2009-09-23
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 147285, Linuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221771
 
Pollutant: Linuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn 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 16 samples were collected, 16 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 (520XWLKRC).
Temporal Representation: Date for this waterbody was collected over the date range 2007-02-08 to 2008-09-17
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 147285, Linuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294976
 
Pollutant: Linuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn 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 15 samples were collected, 15 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-02-16 to 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147286
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Malathion
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.
 
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 147286, Malathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295016
 
Pollutant: Malathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and the results are as follows: 0 of the 16 samples exceeded the water quality threshold for Malathion. Although a total of 20 samples were collected, 4 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: Aquatic life should not be affected unacceptably if the 4-day average concentration of malathion does not exceed 0.028 ug/L (UC Davis Aquatic Life Criteria).
Guideline Reference: Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.
 
Spatial Representation: The samples were collected at 1 monitoring site (520XWLKCH).
Temporal Representation: Data for this waterbody was collected over the date range 2011-01-19 to 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147286, Malathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72152
 
Pollutant: Malathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 23
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 23 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
147256
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Methamidophos
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 147256, Methamidophos
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295231
 
Pollutant: Methamidophos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Methamidophos.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 methamifophos is the USEPA Aquatic Life Benchmark of 4.5 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2013-03-21 and 2013-09-18
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147314
Region 5     
Walker Creek (Glenn 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)(2020)
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 27 samples exceed the evaluation guideline for the aquatic life beneficial use. LOE 72164 has been replaced by LOE 221986 and LOE 221754 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 27 samples exceed the evaluation guideline for the aquatic life beneficial use, 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 147314, Methidathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221754
 
Pollutant: Methidathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147314, Methidathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221986
 
Pollutant: Methidathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147314, Methidathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295255
 
Pollutant: Methidathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Methidathion.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2013-03-21 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147307
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147307, Methiocarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221889
 
Pollutant: Methiocarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 6 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147307, Methiocarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221928
 
Pollutant: Methiocarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147307, Methiocarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294982
 
Pollutant: Methiocarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Methiocarb.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147308
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147308, Methomyl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72166
 
Pollutant: Methomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147308, Methomyl
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 307391
 
Pollutant: Methomyl
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Methomyl.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2018-05-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147287
Region 5     
Walker Creek (Glenn 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)(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 24 samples exceed the WARM criteria.

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 24 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 147287, Methoxychlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72167
 
Pollutant: Methoxychlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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 147287, Methoxychlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295076
 
Pollutant: Methoxychlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Methoxychlor.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 USEPA national ambient water quality criterion for freshwater aquatic life Criterion Continuous Concentration (CCC) expressed as a 4-day average for methoxychlor is 0.03 ug/L.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147288
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147288, Methyl Parathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72182
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 23
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 23 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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 147288, Methyl Parathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296102
 
Pollutant: Methyl Parathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Parathion, Methyl.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147319
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Metolachlor
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147319, Metolachlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295181
 
Pollutant: Metolachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 7
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Metolachlor.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 metolachlor is the USEPA Aquatic Life Benchmark of 1 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147289
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Mirex
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147289, Mirex
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294992
 
Pollutant: Mirex
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Mirex. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The USEPA national recommended criterion continuous concentration for mirex for the protection of freshwater aquatic life is 0.001 µg/L.
Guideline Reference: National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Current as of 08/03/2016.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-03-16 to 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
129058
Region 5     
Walker Creek (Glenn 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 72183 has been replaced by LOE 221828 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 129058, Molinate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 221828
 
Pollutant: Molinate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 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
147290
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Molybdenum
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 147290, Molybdenum
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295032
 
Pollutant: Molybdenum
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Agricultural Supply
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Molybdenum.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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; Fifth Edition. Revised May 2018 (with approved amendments)
 
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. 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 recommended maximum concentration of molybdenum in irrigation water is 0.01 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2011-05-18
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147339
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Monuron
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 147339, Monuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295208
 
Pollutant: Monuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Monuron.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147325
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Naled
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147325, Naled
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295047
 
Pollutant: Naled
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Naled. Although a total of 4 samples were collected, 4 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 naled is the USEPA Aquatic Life Benchmark of 0.01 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-01-19 to 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
149868
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: 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 149868, Nitrogen, ammonia (Total Ammonia)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 292965
 
Pollutant: Nitrogen, ammonia (Total Ammonia)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 1 of 22 samples exceeded the water quality threshold for Ammonia as N.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013 document.
Objective/Criterion Reference: Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2018-12-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147309
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147309, Oryzalin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222175
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147309, Oryzalin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222170
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147309, Oryzalin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295522
 
Pollutant: Oryzalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for Oryzalin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2017-10-25
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147292
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Oxamyl (Vydate)
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 147292, Oxamyl (Vydate)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295547
 
Pollutant: Oxamyl (Vydate)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Oxamyl.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 oxamyl is the USEPA Aquatic Life Benchmark of 27 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147316
Region 5     
Walker Creek (Glenn 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)(2020)
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.

During the 2024 Cycle LOEs were updated due to a reassessment of data based on revised evaluation guidelines for pesticides.

The number of measured exceedances is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicant pollutants (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 this water segment-pollutant combination should not be placed on the CWA section 303(d) List.

Refer to the lines of evidence in this fact sheet for the data and information, sample counts and exceedances, quality assurance documentation, beneficial uses, and water quality objectives or numeric evaluation guidelines relied upon for this decision.
 
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 147316, Oxyfluorfen
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 295311
 
Pollutant: Oxyfluorfen
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 21
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 1 of 21 samples exceeded the water quality threshold for Oxyfluorfen.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).
Guideline Reference: Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2018-12-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147316, Oxyfluorfen
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315344
 
Pollutant: Oxyfluorfen
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).
Guideline Reference: Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKRC (NA).
Temporal Representation: The samples were collected between the dates of 2007-02-08 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
147337
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Paraquat
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147337, Paraquat
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296417
 
Pollutant: Paraquat
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Paraquat. Although a total of 3 samples were collected, 3 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 paraquat is the USEPA Aquatic Life Benchmark of 0.396 ug/L for a nonvascular plant (acute) for Paraquat dichloride.
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2017-10-25 to 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147320
Region 5     
Walker Creek (Glenn 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)(2020)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147320, Pendimethalin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222117
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 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 147320, Pendimethalin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296177
 
Pollutant: Pendimethalin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Pendimethalin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2017-10-25 and 2017-10-25
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147340
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Permethrin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147340, Permethrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296302
 
Pollutant: Permethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 4 samples were collected, 4 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 chronic concentration goal for permethrin is 1 ng/L (expressed as a 4-day average).  If the freely dissolved concentrations of Permethrin were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Water Quality Criteria Report for Permethrin
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147321
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147321, Phorate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296053
 
Pollutant: Phorate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Phorate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147321, Phorate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222281
 
Pollutant: Phorate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147321, Phorate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222286
 
Pollutant: Phorate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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
147327
Region 5     
Walker Creek (Glenn 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)(2020)
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.

During the 2024 Cycle LOEs were updated due to a reassessment of data based on revised evaluation guidelines for pesticides.

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 147327, Phosmet
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315391
 
Pollutant: Phosmet
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for phosmet is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (NA).
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147327, Phosmet
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315409
 
Pollutant: Phosmet
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: The evaluation guideline for phosmet is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKRC (NA).
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147327, Phosmet
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296145
 
Pollutant: Phosmet
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Phosmet.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 0.75 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2013-03-21 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
129059
Region 5     
Walker Creek (Glenn 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: 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 twenty samples exceed the evaluation guideline. LOE 72234 has been replaced by LOE 222183 and LOE 222163 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. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the twenty 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: 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 129059, Prometon (Prometone)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222163
 
Pollutant: Prometon (Prometone)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 129059, Prometon (Prometone)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222183
 
Pollutant: Prometon (Prometone)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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
154505
Region 5     
Walker Creek (Glenn 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)(2020)
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.

During the 2024 Cycle LOEs were updated due to a reassessment of data based on revised evaluation guidelines for pesticides.

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. 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 154505, Prometryn
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315492
 
Pollutant: Prometryn
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Prometryn does not exceed 0.562 ug/L in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water Quality Criteria Report for Prometryn Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (NA).
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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 154505, Prometryn
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315555
 
Pollutant: Prometryn
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Prometryn does not exceed 0.562 ug/L in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water Quality Criteria Report for Prometryn Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKRC (NA).
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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
147322
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Propachlor
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 147322, Propachlor
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296224
 
Pollutant: Propachlor
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Propachlor.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 propachlor is the USEPA Aquatic Life Benchmark of 13.5 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
129070
Region 5     
Walker Creek (Glenn 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 72251 has been replaced by LOE 222322 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 129070, Propargite
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222322
 
Pollutant: Propargite
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 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
129076
Region 5     
Walker Creek (Glenn 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: 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 72252 has been replaced by LOE 222386 and LOE 222385 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 129076, Propazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222386
 
Pollutant: Propazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 129076, Propazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222385
 
Pollutant: Propazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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
147338
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Propiconazole
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147338, Propiconazole
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296173
 
Pollutant: Propiconazole
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Propiconazole.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 Propiconazole is the USEPA Aquatic Life Benchmark of 15 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-05-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147296
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Propoxur
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 147296, Propoxur
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296174
 
Pollutant: Propoxur
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Propoxur.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 propoxur is the USEPA Aquatic Life Benchmark of 5.5 ug/L for invertebrates (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147341
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Pyraclostrobin
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147341, Pyraclostrobin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296322
 
Pollutant: Pyraclostrobin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Pyraclostrobin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 pyraclostrobin is the USEPA Aquatic Life Benchmark of 1.5 ug/L for a nonvascular plant (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-07-18 and 2018-07-18
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147303
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Pyrethroids
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147303, Pyrethroids
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296531
 
Pollutant: Pyrethroids
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyrethroids. Although a total of 5 samples were collected, 5 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: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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 summed ratios of the pyrethroid pesticides bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda-cyhalothrin, permethrin and their respective chronic concentration goals are not to exceed 1. If the freely dissolved concentrations of these pesticides were reported or could be calculated then these values were used for this assessment.  In the absence of freely dissolved concentrations, total concentrations were used.
Guideline Reference: Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147344
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Pyridaben
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147344, Pyridaben
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296574
 
Pollutant: Pyridaben
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Pyridaben. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 pyridaben is the USEPA Aquatic Life Benchmark of 0.044 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-08-22 to 2018-08-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147310
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Siduron
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 147310, Siduron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296719
 
Pollutant: Siduron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Siduron.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 siduron is the USEPA Aquatic Life Benchmark of 6 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147297
Region 5     
Walker Creek (Glenn 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)(2020)
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 72254 has been replaced by LOE 222444 and LOE 222600 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 147297, Simazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296480
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Simazine.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-01-19 and 2015-03-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147297, Simazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222600
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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 147297, Simazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222444
 
Pollutant: Simazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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
147257
Region 5     
Walker Creek (Glenn County)
 
Pollutant: T-Fluvalinate
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 147257, T-Fluvalinate
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296517
 
Pollutant: T-Fluvalinate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for T-Fluvalinate.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 tau-fluvalinate is the USEPA Aquatic Life Benchmark of 0.064 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147311
Region 5     
Walker Creek (Glenn 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)(2020)
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.
 
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 147311, Tebuthiuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222508
 
Pollutant: Tebuthiuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 16 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 and 2008-09-17
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 147311, Tebuthiuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222528
 
Pollutant: Tebuthiuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 6
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 6 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 (520XWLKCH)
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-09-23
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 147311, Tebuthiuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296576
 
Pollutant: Tebuthiuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Tebuthiuron.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147298
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Tetrachlorvinphos
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 147298, Tetrachlorvinphos
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296767
 
Pollutant: Tetrachlorvinphos
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm 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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 14 samples exceeded the water quality threshold for Tetrachlorvinphos.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 stirophos (tetrachlorvinphos) is the USEPA Aquatic Life Benchmark of 0.125 ug/L for an invertebrate (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2014-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147258
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Tetramethrin
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 147258, Tetramethrin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296810
 
Pollutant: Tetramethrin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Tetramethrin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 tetramethrin is the USEPA Aquatic Life Benchmark of 1.85 ug/L for a fish (acute).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-09-19
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
129077
Region 5     
Walker Creek (Glenn 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: 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 129077, Thiobencarb
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 222579
 
Pollutant: Thiobencarb
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed ILRP_SVWQC data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 (520XWLKRC)
Temporal Representation: The samples were collected between the dates of 2007-02-08 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
147299
Region 5     
Walker Creek (Glenn 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)(2018)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147299, Toxaphene
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72003
 
Pollutant: Toxaphene
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn 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 Walker Creek (Glenn County) was collected at 1 monitoring site [Walker Creek at County Road 48 - 520XWLKRC]
Temporal Representation: Data was collected over the time period 2/8/2007-8/20/2008.
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 147299, Toxaphene
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296907
 
Pollutant: Toxaphene
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
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 Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Toxaphene. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The toxaphene criterion for the protection of human health from consumption of organisms only is 0.00075 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-03-16 to 2011-03-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147299, Toxaphene
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296911
 
Pollutant: Toxaphene
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Toxaphene. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: 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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2011-03-16 to 2011-03-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147301
Region 5     
Walker Creek (Glenn 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)(2020)
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: During the 2024 Cycle LOEs were updated due to a reassessment of data based on revised evaluation guidelines for pesticides.

Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147301, Trifluralin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315393
 
Pollutant: Trifluralin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Trifluralin does not exceed 0.33 ug/L in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water Quality Criteria Report for Trifluralin Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKRC (NA).
Temporal Representation: The samples were collected between the dates of 2007-02-08 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 147301, Trifluralin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 315431
 
Pollutant: Trifluralin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition-3890 data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 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: 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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Trifluralin does not exceed 0.33 ug/L in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water Quality Criteria Report for Trifluralin Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (NA).
Temporal Representation: The samples were collected between the dates of 2009-02-19 and 2009-06-18
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 147301, Trifluralin
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296798
 
Pollutant: Trifluralin
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 1
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Trifluralin.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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: UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Trifluralin does not exceed 0.33 ug/L in the water column more than once every three years on average (Bower, et al. 2017).
Guideline Reference: Water Quality Criteria Report for Trifluralin Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology University of California, Davis.
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-05-16 and 2018-05-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147302
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Zinc
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147302, Zinc
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296839
 
Pollutant: Zinc
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 2
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Zinc.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The dissolved zinc criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 120 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2018-06-20 and 2018-07-18
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147345
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Ziram
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of the available data and information, SWRCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
 
 
Line of Evidence (LOE) for Decision ID 147345, Ziram
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296946
 
Pollutant: Ziram
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Ziram. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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 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 ziram is the USEPA Aquatic Life Benchmark of 1.4 ug/L for a fish (chronic).
Guideline Reference: OPP Aquatic Life Benchmarks
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: Data for this waterbody were collected over the date range 2018-05-16 to 2018-05-16
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147268
Region 5     
Walker Creek (Glenn 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)(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.

Three lines of evidence is available in the administrative record to assess this pollutant. Zero of the 24 samples exceed the criteria for aquatic life. Additionally, zero of 5 samples exceed the criteria 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 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 24 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 147268, alpha-Endosulfan (Endosulfan 1)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72070
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 agvaiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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 147268, alpha-Endosulfan (Endosulfan 1)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294151
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan I.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endosulfan I (alpha-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.028 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147268, alpha-Endosulfan (Endosulfan 1)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 293925
 
Pollutant: alpha-Endosulfan (Endosulfan 1)
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan I.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endosulfan I (alpha-endosulfan) criterion for the protection human health from the consumption of organisms only is 240 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
147294
Region 5     
Walker Creek (Glenn 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)(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.
 
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 147294, beta-Endosulfan (Endosulfan 2)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294147
 
Pollutant: beta-Endosulfan (Endosulfan 2)
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: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan II.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endosulfan II (beta-endosulfan) criterion to protect human health from the consumption of organisms only is 240 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147294, beta-Endosulfan (Endosulfan 2)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 294149
 
Pollutant: beta-Endosulfan (Endosulfan 2)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 5
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Endosulfan II.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: The endosulfan II (beta-endosulfan) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.028 ug/L (California Toxics Rule, 2000).
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: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2011-02-16 and 2015-04-22
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
Line of Evidence (LOE) for Decision ID 147294, beta-Endosulfan (Endosulfan 2)
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72086
 
Pollutant: beta-Endosulfan (Endosulfan 2)
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 agvaiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 19 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-5/20/2009.
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
147295
Region 5     
Walker Creek (Glenn County)
 
Pollutant: pH
Final Listing Decision: Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: New Decision
Revision Status Revised
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy.

The number of measured exceedances is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for conventional pollutants (Table 3.2 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 this water segment-pollutant combination should not be placed on the CWA section 303(d) List.

Refer to the lines of evidence in this fact sheet for the data and information, sample counts and exceedances, quality assurance documentation, beneficial uses, and water quality objectives or numeric evaluation guidelines relied upon for this decision.
 
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 147295, pH
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 296159
 
Pollutant: pH
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 74
Number of Exceedances: 4
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Sacramento Valley Water Quality Coalition data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 4 of 74 samples exceeded the water quality threshold for pH.
Data Reference: Field, Habitat, Toxicity, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 5.
 
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; Fifth Edition. Revised May 2018 (with approved amendments)
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at 1 monitoring site: 520XWLKCH (Walker Creek near 99W and CR33).
Temporal Representation: The samples were collected between the dates of 2010-09-23 and 2020-08-20
Environmental Conditions:
QAPP Information: Central Valley RWQCB. 2021. QAPP Reference for Irrigated Lands Regulatory Program.
QAPP Information Reference(s): QAPP Reference for Irrigated Lands Regulatory Program
 
 
DECISION ID
74295
Region 5     
Walker Creek (Glenn 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 22 water sample results 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. None of the 22 water sample results exceed the 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 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 74295, Ammonia as N, Total
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 79035
 
Pollutant: Ammonia as N, Total
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Warm Freshwater Habitat
Aquatic Life Use: Warm Freshwater Habitat
 
Number of Samples: 22
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Twenty-two water samples collected from Walker Creek (Glenn County) by the Sacramento Valley Water Quality Coalition were analyzed for ammonia, pH and temperature. None of the 22 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 22 water samples were collected from Walker Creek (Glenn County) at two monitoring sites [Walker Creek at County Road 48 - 520XWLKRC and Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: The 22 water samples were collected from Walker Creek (Glenn County) between 2/8/2007 and 9/23/2009
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
87356
Region 5     
Walker Creek (Glenn 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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the 18 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 18 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 87356, Arsenic
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72071
 
Pollutant: Arsenic
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 18
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 20 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-3/17/2009.
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
92040
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Boron
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 92040, Boron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 79535
 
Pollutant: Boron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Agricultural 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 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 Walker Creek (Glenn County) was collected at 1 monitoring site [ Walker Creek at County Road 48 - 520XWLKRC]
Temporal Representation: Data was collected over the time period 2/8/2007-9/17/2008.
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
89719
Region 5     
Walker Creek (Glenn 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 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 20 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 20 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 89719, Cyanazine
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72102
 
Pollutant: Cyanazine
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 20
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 20 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-6/18/2009.
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
92192
Region 5     
Walker Creek (Glenn 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 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 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 22 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 92192, N-(4-Chlorophenyl) -N' methylurea / Monuron
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72184
 
Pollutant: N-(4-Chlorophenyl) -N' methylurea / Monuron
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 22
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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 22 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
91543
Region 5     
Walker Creek (Glenn 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 91543, Parathion
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72210
 
Pollutant: Parathion
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Parathion, Ethyl. Twenty-three 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 Walker Creek (Glenn County) was collected at 2 monitoring sites [Walker Creek at County Road 48 - 520XWLKRC, Walker Creek near 99W and CR33 - 520XWLKCH]
Temporal Representation: Data was collected over the time period 2/8/2007-9/23/2009.
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
100410
Region 5     
Walker Creek (Glenn County)
 
Pollutant: Selenium
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 100410, Selenium
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72253
 
Pollutant: Selenium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm 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 Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 1 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 Walker Creek (Glenn County) was collected at 1 monitoring site [Walker Creek at County Road 48 - 520XWLKRC]
Temporal Representation: Data was collected over the time period 2/8/2007-9/17/2008.
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
91603
Region 5     
Walker Creek (Glenn 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.

One line of evidence is available in the administrative record to assess this pollutant. Zero of the eight 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 eight 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 91603, Thiobencarb/Bolero
Region 5     
Walker Creek (Glenn County)
 
LOE ID: 72001
 
Pollutant: Thiobencarb/Bolero
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Warm Freshwater Habitat
 
Number of Samples: 8
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed Ag Waiver data for Walker Creek (Glenn County) to determine beneficial use support and results are as follows: 0 of 8 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 Walker Creek (Glenn County) was collected at 1 monitoring site [Walker Creek at County Road 48 - 520XWLKRC]
Temporal Representation: Data was collected over the time period 2/8/2007-12/19/2007.
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.