# Draft 2008 California 303(d)/305(b) Integrated Report

# Supporting Information

## Regional Board 5 - Central Valley Region

Water Body Name: | Orestimba Creek (above Kilburn Road)
Water Body ID: | CAR5422003219990126113826
Water Body Type: | River & Stream

DECISION ID | 7106
Pollutant: | DDE
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)(2006)
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2011
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for removal from the 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. One lines of evidence are available in the administrative record to assess pollutant. Six of samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Six of 6 samples exceeded the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 μg/L for DDE based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: | N/A
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 7106

LOE ID: | 23174
Pollutant: | DDE
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 6
Number of Exceedances: | 6
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Six water samples were taken from Orestimba Creek between January, 2006 and August, 2006. All of the available six water samples exceed the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 µg/L for DDE based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms (4,4¿-DDE).
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | - Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007a). Pesticides: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000)Inland Surface Waters based on drinking water and aquatic organism consumption. The criteria are based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) for DDE of 0.00059 µg/L.
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
| Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33 in Stanislaus County, California.
Temporal Representation: | Samples were collected between January, 2006 and August, 2006. Samples were collected at monthly intervals.
Environmental Conditions: |
QAPP Information: | Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 4499
Pollutant: | DDE
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Not Recorded
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Asses Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: | Placeholder reference pre-2006 303(d)
Water Quality Objective/Criterion: | Unspecified
Objective/Criterion Reference: | Placeholder reference pre-2006 303(d)
Evaluation Guideline: | Unspecified
Guideline Reference: | Placeholder reference pre-2006 303(d)
Spatial Representation: | Unspecified
Temporal Representation: | Unspecified
Environmental Conditions: | Unspecified
QAPP Information: | Unspecified
QAPP Information Reference(s):

DECISION ID | 13611
Pollutant: | DDD
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 2 samples exceeded the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00083 μg/L for DDD based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13611

LOE ID: | 23173
Pollutant: | DDD
LOE Subgroup: | Pollutant-Sediment
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 2
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Two water samples were taken from Orestimba Creek between July 2006 and August 2006. One of the available two water samples exceeded the California Toxic Rule/USEPA (CTR/USEPA) criteria limit for DDD of 0.00083 µg/L based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | - Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007a). Pesticides: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000)Inland Surface Waters based on drinking water and aquatic organism consumption. The criteria are based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) for DDD of 0.00083 µg/L.
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
| Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33 in Stanislaus County, California.
Temporal Representation: | Samples were collected between July 2006 and August 2006. Samples were collected at monthly intervals.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 14852
Pollutant: | Disulfoton
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of 172 water samples exceed the Evaluation Guideline for the naarative toxicity water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 172 usable water sample results exceeded the USEPA National Ambient Water Quality Criteria Freshwater Aquatic Life Protection Maximum (Instantaneous) value for disulforon (0.05 ug/L) and, therefore, none of the samples exceeded the narrative toxicity objective, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Twenty-four additional water samples had disulfoton concentrations less than the quantitation limits, and the quantitation limits were greater than the Evaluation Guideline value. Therefore, the samples were not used in this analysis in accordance with section 6.1.5.5 of the Listing Policy 5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14852

LOE ID: | 26167
Pollutant: | Disulfoton
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 151
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | One hundred fifty one water samples were collected from Orestimba Creek at River Road and analyzed for disulfoton. None of the 151 water samples contained disulfoton at concentrations that exceed the Evaluation Guideline of 0.05 µg/L.
Data Reference: | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses (CVRWQCB, 2007). All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | USEPA National Ambient Water Quality disulfoton criterion for freshwater aquatic life protection, maximum concentration of 0.05 ug/L.
Guideline Reference: | National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology. 4304T
Spatial Representation: | Samples were collected from Orestimba Creek at River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek between January 6, 2000 and September 7, 2005, as reported in the DPR Surface Water Database, at various intervals, including daily, twice weekly, weekly, twice monthly, monthly, every two months, and every 3 to 6 months.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Minimum requirements for the Surface Water Database are: Name of the sampling agency or organization Date that each sample was collected Date of each sample analysis County where samples were taken Detailed sampling location information (including latitude and longitude or township/range/section if available), detailed map or description of each sampling site (i.e., address, cross roads, etc.) Name or description of water body sampled Name of the active ingredient analyzed for; concentration detected (with unit of measurement), and limit of quantitation Description of analytical QA/QC plan, or statement that no formal plan exists Additional optional requirements are included on DPRs webpage at http://www.cdpr.ca.gov/docs/emon/surfwtr/caps/req.htm
QAPP Information Reference(s): | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
LOE ID: | 26171
Pollutant: | Disulfoton
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 Asses Water Quality: | Forty-one water samples were collected from Orestimba Creek, under the Irrigated Lands Regulatory Program, between July 2004 and August 2006. Zero of the 7 water samples contained disulfoton at concentrations that exceed the Evaluation Guideline of 0.05 ug/L. Twenty-four of the samples had quantitation limits greater than the Evaluation Guideline value and, therefore, according to Section 6.1.5.5 of the Listing Policy these sample results were not included in this assessment.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | USEPA National Ambient Water Quality Disulfoton Criterion for freshwater aquatic life protection, maximum concentration of 0.05 ug/L.
Guideline Reference: | Compilation of Water Quality Goals - 2007 for toxicity data
Spatial Representation: | Water samples were collected from Orestimba Creek at Kilburn Road, Highway 33, and River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek at Kilburn Road on: July 15 and 29, 2004; August 12 and 26, 2004; and September 9, 2004. Water samples were collected from Orestimba Creek at Highway 33 on: July 6, 2004; August 10, 2004; December 29, 2004; monthly between February 16 and August 9, 2005; January 3, 2006; and monthly between March 14 and August 9, 2006. Water samples were collected from Orestimba Creek at River Road on: July 6, 2004; August 10, 2004; December 29, 2004; monthly between February 16 and August 9, 2005; January 3, 2006; and monthly between March 14 and August 9, 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826 ) requirements.
QAPP Information Reference(s):
LOE ID: | 26169
Pollutant: | Disulfoton
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 Asses Water Quality: | Four water samples were collected from Orestimba Creek, under the Pesticide TMDL program, between January and March 2006. Zero of the 4 water samples contained disulfoton at a concentration that exceeds the Evaluation Guideline of 0.05 ug/L.
Data Reference: | Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | USEPA National Ambient Water Quality disulfoton criterion for freshwater aquatic life protection, maximum concentration of 0.05 ug/L.
Guideline Reference: | Compilation of Water Quality Goals - 2007 for toxicity data
Spatial Representation: | Water samples were collected from Orestimba Creek at Kilburn Road.
Temporal Representation: | Water samples were collected from Orestimba Creek on 14 and 15 January 2006, 28 February 2006, and 1 March 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. All sampling, analysis and QA/QC protocols are described in a QAPP (Calanchini et al., 2006).
QAPP Information Reference(s):

DECISION ID | 14854
Pollutant: | Methomyl
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. One of the samples exceed the Evaluation Guideline (4-day average criterion of 0.52 ug/L) for the narrative toxicity water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 7 water samples exceeded the methomyl Evaluation Guideline for 4-day average concentration of 0.52 ug/L and, therefore one sample exceeds the narrative toxicity 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.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14854

LOE ID: | 26173
Pollutant: | Methomyl
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 7
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Seven water samples were collected from Orestimba Creek, under the Irrigated Lands Regulatory Program, monthly or twice per month between July 2004 and August 2006. One of the 7 water samples contained methomyl at concentrations that exceed the Evaluation Guideline for the 4-day average concentration (0.52 ug/L). Zero of the 7 water samples contained methomyl at concentrations that exceed the Evaluation Guideline for the 1-hour maximum concentration (5.5 ug/L).
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | California Department of Fish and Game Hazard Assessment methomyl 4-day average concentration (0.52 ug/L) and 1-hour maximum concentration (5.5 ug/L).
Guideline Reference: | Compilation of Water Quality Goals - 2007 for toxicity data
Spatial Representation: | Water samples were collected from Orestimba Creek at Kilburn Road and River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek monthly or twice per month between July 2004 and August 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826 ) requirements.
QAPP Information Reference(s):

DECISION ID | 14856
Pollutant: | Prometryn
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 54 samples exceeded the narrative toxicity 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.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14856

LOE ID: | 26176
Pollutant: | Prometryn
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 Asses Water Quality: | Four water samples (two sets of duplicate samples, representing two daily-averaged water sample results for prometryn) were collected from Orestimba Creek at River Road on January 3, 2006 and April 4, 2006, under the Irrigated Lands Regulatory Program.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
| Correspondence between the Department of Pesticide Regulation and Central Valley Regional Water Quality Control Board regarding water quality data for waterbodies in the Central Valley
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses (CVRWQCB, 2007).All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | The EC50 for the most sensitive species freshwater species (Navicula pelliculosa, a freshwater diatom) is 1 ug/L (U.S. EPA, 2000).
Guideline Reference: | Ecotoxicity database. U.S. Environmental Protection Agency, Office of Pesticide Programs
Spatial Representation: | Water samples were collected from Orestimba Creek at River Road.
Temporal Representation: | Two (duplicate) water samples were collected from Orestimba Creek at River Road on January 3, 2006 and on April 4, 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826 ) requirements.
QAPP Information Reference(s): | Standard Operating Procedure for Conducting Surface Water Monitoring for Pesticides
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
LOE ID: | 26175
Pollutant: | Prometryn
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 52
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Fifty-two water samples were collected from Orestimba Creek at River Road from January 2000 through September 2002 representing 52 concentrations.
Data Reference: | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
| Correspondence between the Department of Pesticide Regulation and Central Valley Regional Water Quality Control Board regarding water quality data for waterbodies in the Central Valley
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses (CVRWQCB, 2007).All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | The EC50 for the most sensitive species freshwater species (Navicula pelliculosa, a freshwater diatom) is 1 ug/L (U.S. EPA, 2000).
Guideline Reference: | Ecotoxicity database. U.S. Environmental Protection Agency, Office of Pesticide Programs
Spatial Representation: | Samples were collected from Orestimba Creek at River Road.
Temporal Representation: | Samples were collected at variable intervals (biweekly, weekly, monthly) from January 2000 through September 2002.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Minimum requirements for the CDPR Surface Water Database are: Name of the sampling agency or organization, Date that each sample was collected, Date of each sample analysis, County where samples were taken, Detailed sampling location information (including latitude and longitude or township/range/section if available), detailed map or description of each sampling site (i.e., address, cross roads, etc.), Name or description of water body sampled, Name of the active ingredient analyzed for; concentration detected (with unit of measurement), and limit of quantitation, Description of analytical QA/QC plan, or statement that no formal plan exists. Additional optional requirements are included on DPR's webpage at http://www.cdpr.ca.gov/docs/emon/surfwtr/caps/req.htm
QAPP Information Reference(s): | Standard Operating Procedure for Conducting Surface Water Monitoring for Pesticides

DECISION ID | 14868
Pollutant: | Propargite
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the Evaluation Guideline for the narrative toxicity water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 147 samples exceeded the Evaluation Guideline for propargite 6 ug/L, which is one-tenth of the LC50 for the most-sensitive freshwater species, Cyprinodon variegatus, Sheepshead minnow). Therefore, none of the 147 sample results exceed the narrative toxicity objective, and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy.4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14868

LOE ID: | 26178
Pollutant: | Propargite
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 115
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | One hundred-fifteen water samples were collected from Orestimba Creek at River Road and analyzed for propargite. None of the 115 water samples contained propargite at concentrations that exceed the Evaluation Guideline of 6 µg/L.
Data Reference: | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Where valid testing has developed 96 hour LC50 values for aquatic organisms (the concentration that kills one half of the test organisms in 96 hours), 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. Other available technical information on the pesticide (such as Lowest Observed Effect Concentrations and No Observed Effect Levels), the water bodies and the organisms involved will be evaluated to determine if lower concentrations are required to meet the narrative objectives. The 96-hour LC50 for propargite for the most-sensitive freshwater species (Cyprinodon variegatus, Sheepshead minnow) is 60 µg/L. Therefore, the one-tenth LC50 value is 6 µg/L.
Guideline Reference: | National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology. 4304T
Spatial Representation: | Samples were collected from Orestimba Creek at River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek at River Road between January 6, 2000 and September 7, 2005, as reported in the DPR Surface Water Database, at various intervals, including daily, twice weekly, weekly, twice monthly, monthly, every two months, and every 3 to 6 months.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Minimum requirements for the Surface Water Database are: Name of the sampling agency or organization Date that each sample was collected Date of each sample analysis County where samples were taken Detailed sampling location information (including latitude and longitude or township/range/section if available), detailed map or description of each sampling site (i.e., address, cross roads, etc.) Name or description of water body sampled Name of the active ingredient analyzed for; concentration detected (with unit of measurement), and limit of quantitation Description of analytical QA/QC plan, or statement that no formal plan exists Additional optional requirements are included on DPRs webpage at http://www.cdpr.ca.gov/docs/emon/surfwtr/caps/req.htm
QAPP Information Reference(s): | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
LOE ID: | 26180
Pollutant: | Propargite
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 32
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Thirty-six water samples (including 8 duplicate samples) were collected from Orestimba Creek, under the Pesticide TMDL program, between January and August 2003, representing 28 daily-averaged propargite concentrations. Zero of the 28 water samples contained propargite at a concentration that exceeds the Evaluation Guideline of 6 ug/L. Four water samples were collected from Orestimba Creek, under the Pesticide TMDL program, between January 14, 2006 and March 1, 2006.
Data Reference: | Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Where valid testing has developed 96 hour LC50 values for aquatic organisms (the concentration that kills one half of the test organisms in 96 hours), 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. Other available technical information on the pesticide (such as Lowest Observed Effect Concentrations and No Observed Effect Levels), the water bodies and the organisms involved will be evaluated to determine if lower concentrations are required to meet the narrative objectives. The 96-hour LC50 for propargite for the most-sensitive freshwater species (Cyprinodon variegatus, Sheepshead minnow) is 60 µg/L. Therefore, the one-tenth LC50 value is 6 µg/L.
Guideline Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| Compilation of Water Quality Goals - 2007 for toxicity data
Spatial Representation: | Water samples were collected from Orestimba Creek at River Road (2003) and at Kilburn Road (2006).
Temporal Representation: | Water samples were collected from Orestimba Creek: on January 9, 2003; daily between February 13 and 17, 2003; on March 13, 2003; daily between March 15 and 18, 2003; weekly or every two weeks between March 27, 2003 and August 28, 2003; on January 14 and 15, 2006; on February 28, 2006; and on March 1, 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. All sampling, analysis and QA/QC protocols are described in a QAPP (Calanchini et al., 2006).
QAPP Information Reference(s): | Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports

DECISION ID | 13612
Pollutant: | Salinity
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Eleven of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eleven of 133 samples exceeded the water quality objectives for electrical conductivity and total dissolved solids (collectively salinity) and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13612

LOE ID: | 22900
Pollutant: | Salinity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 72
Number of Exceedances: | 9
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Seventy-two samples were taken from Orestimba Creek between 2000 and 2006. Nine of the 72 samples exceed the California Secondary MCL for Municipal Water Quality Objectives for electrical conductivity in surface water.
Data Reference: | Monitoring Data from the Surface Water Ambient Monitoring Program (SWAMP), San Joaquin River Basin - 2007 Data Review
Water Quality Objective/Criterion: | The water quality objective used was the California Secondary MCL recommended level of 900 uS/cm. The Basin Plan includes chemical constituent water quality objectives that include (by reference) secondary maximum contaminant levels (MCL¿s) protective of MUN (CVRWQCB, 2007a).The secondary MCL¿s for electrical conductivity provide a range of values including a recommended level (900 uS/cm), upper level (1600 uS/cm) and a short-term level (2200 uS/cm). The ¿recommended¿ concentration was used as it is intended to be protective of all drinking water uses. Though individual listing evaluations did not look at the water supply source serving the given geographic area, there are certain areas that receive supply waters (such as the Delta Mendota Canal) that at times may be elevated above the recommended level of the secondary MCL. Where future information is made available to document this to be the case, these water bodies may be re-evaluated in future listing cycles.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring. http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Anderson, Bell Road, Highway 33, and Orestimba Road in Stanislaus County.
Temporal Representation: | Samples were collected between November 2004 and November 2005. Samples were collected at bi-weekly intervals.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with the State Water Resources Control Board's Quality Assurance Program Plan for the State of California's Surface Water Ambient Monitoring Program.
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
LOE ID: | 22899
Pollutant: | Salinity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 31
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Thirty-one samples were taken from Orestimba Creek between 2004 and 2006. None of the thirty-one samples exceed the California Secondary MCL for Municipal Water Quality Objectives for electrical conductivity in surface water.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | The water quality objective used was the California Secondary MCL recommended level of 900 uS/cm. The Basin Plan includes chemical constituent water quality objectives that include (by reference) secondary maximum contaminant levels (MCL¿s) protective of MUN (CVRWQCB, 2007a).The secondary MCL¿s for electrical conductivity provide a range of values including a recommended level (900 uS/cm), upper level (1600 uS/cm) and a short-term level (2200 uS/cm). The ¿recommended¿ concentration was used as it is intended to be protective of all drinking water uses. Though individual listing evaluations did not look at the water supply source serving the given geographic area, there are certain areas that receive supply waters (such as the Delta Mendota Canal) that at times may be elevated above the recommended level of the secondary MCL. Where future information is made available to document this to be the case, these water bodies may be re-evaluated in future listing cycles.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring. http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33 in Stanislaus County.
Temporal Representation: | Samples were collected between July 2004 and October 2006. Samples were collected at monthly intervals.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 22901
Pollutant: | Salinity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 30
Number of Exceedances: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Thirty samples were taken from Orestimba Creek between 2004 and 2006. Two of the thirty samples exceed the California Secondary MCL for Municipal Water Quality Objectives for total dissolved solids in surface water.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | The water quality objective used was the California Secondary MCL recommended level of 500 mg/L. The Basin Plan includes chemical constituent water quality objectives that include (by reference) secondary maximum contaminant levels (MCL¿s) protective of MUN (CVRWQCB, 2007a).The secondary MCL¿s for TDS provide a range of values including a recommended level (500 mg/L), upper level (1000 mg/L) and a short-term level (1500 mg/L). The ¿recommended¿ concentration was used as it is intended to be protective of all drinking water uses. Though individual listing evaluations did not look at the water supply source serving the given geographic area, there are certain areas that receive supply waters (such as the Delta Mendota Canal) that at times may be elevated above the recommended level of the secondary MCL. Where future information is made available to document this to be the case, these water bodies may be re-evaluated in future listing cycles.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring. http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33 in Stanislaus County.
Temporal Representation: | Samples were collected between July 2004 and April 2006. Samples were collected at monthly intervals.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 13613
Pollutant: | Selenium
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of 9 samples exceeded the selenium 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.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13613

LOE ID: | 22931
Pollutant: | Selenium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 9
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | The Westside San Joaquin River Water Quality Coalition collected a total of 9 samples from 1 July 2004 to 31 October 2006. None of the samples collected exceeded the evaluation objective.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | CTR criterion of 5 ug/L, total recoverable Se, for the protection of freshwater aquatic life (4-day average concentration to protect from extended period of exposure).
Objective/Criterion Reference: | Water Quality 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
| Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at two locations: Orestimba Creek at Highway 33 and Orestimba Creek at Kilburn Road.
Temporal Representation: | Monthly sampling occurred during the irrigation season(s).
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 13615
Pollutant: | Simazine
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of 13 samples exceeded the drinking water standard (4 µg/L) 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.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13615

LOE ID: | 22918
Pollutant: | Simazine
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 13
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | 13 water samples were collected from Orestimba Creek from July 2004 through August 2006, representing 13 concentrations.0 of 13 concentrations exceeded the MCL (4 µg/L).
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | At a minimum, water designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the maximum contaminant levels (MCLs) specified in the following provisions of Title 22 of the California Code of Regulations, which are incorporated by reference into this plan: Tables 64431-A (Inorganic Chemicals) and 64431-B (Fluoride) of Section 64431, Table 64444-A (Organic Chemicals) of Section 64444, and Tables 64449-A (Secondary Maximum Contaminant Levels-Consumer Acceptance Limits) and 64449-B (Secondary Maximum Contaminant Levels-Ranges) of Section 64449. The Maximum Contaminant Level (MCL) for simazine is 4 ug/L.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring. http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx
Evaluation Guideline: |
Guideline Reference: | California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring. http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33.
Temporal Representation: | Samples were collected biweekly or monthly from July 2004 through September 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 13616
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
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Three of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Three of 110 samples exceeded the pH objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13616

LOE ID: | 22906
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 38
Number of Exceedances: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | The Westside San Joaquin Water Quality Coalition collected 38 samples from July 2004 to October 2006. Two out of 38 samples were outside the acceptable range; one sample was higher than the acceptable range and one sample was lower than the acceptable range.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | The pH of water shall not be depressed below 6.5,raised above 8.5, or changed at any time more than 0.5 units from normal ambient pH.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Measurement of pH within the range of 6.5 and 8.5
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33.
Temporal Representation: | Sampling occurred from July 2004 to October 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 22907
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 72
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | The Central Valley Regional Water Quality Control Board Surface Water Ambient Monitoring Program collected 72 samples from November 2004 to November 2005. One out of 72 samples was outside the acceptable range; the sample was higher than the acceptable range.
Data Reference: | Monitoring Data from the Surface Water Ambient Monitoring Program (SWAMP), San Joaquin River Basin - 2007 Data Review
Water Quality Objective/Criterion: | The pH of water shall not be depressed below 6.5,raised above 8.5, or changed at any time more than 0.5 units from normal ambient pH.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Measurement of pH within the range of 6.5 and 8.5
Guideline Reference:
Spatial Representation: | Samples were collected from four locations: Orestimba Creek at Anderson, Orestimba Creek at Bell road, Orestimba Creek at Highway 33, and Orestimba Creek at Orestimba Road.
Temporal Representation: | Sampling occurred from November 2004 to November 2005.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with the State Water Resources Control Board's Quality Assurance Program Plan for the State of California's Surface Water Ambient Monitoring Program.
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 13223
Pollutant: | DDT
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 2 samples exceed the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 μg/L for DDT based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13223

LOE ID: | 22890
Pollutant: | DDT
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: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Two water samples were taken from Orestimba Creek between July 2006 and August 2006. All of the available two water samples exceeded the California Toxic Rule/USEPA (CTR/USEPA) criteria limit of 0.00059 µg/L for DDT based on a human health carcinogenic risk level of 10-6 for consumption of water and aquatic organisms for DDT.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | - Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007a). Pesticides: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000)Inland Surface Waters based on drinking water and aquatic organism consumption. The criteria are based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) with a limit of less than 0.00059 µg/L for DDT.
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
| Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33 in Stanislaus County, California.
Temporal Representation: | Samples were collected between July 2006 and August 2006. Samples were collected at monthly intervals.
Environmental Conditions: |
QAPP Information: | Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 14392
Pollutant: | Dacthal
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Thirteen of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Thirteen of 131 water samples exceed the Evaluation Guideline for Dacthal (DCPA), which is based on the U.S. Environmental Protection Agency National Ambient Water Quality Criteria value of 0.008 µg/L, and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14392

LOE ID: | 26109
Pollutant: | Dacthal
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 131
Number of Exceedances: | 13
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Thirteen of 131 water samples collected from Colusa Basin Drain by the United States Geological Survey, under the National Water Information System program, between November 1996 and April 1998, exceeded the Evaluation Guideline (USEPA National Ambient Water Quality Criterion for dacthal (DCPA)) of 0.008 µg/L.
Data Reference: | National Water Quality Assessment database, Sacramento Study Unit 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 (CRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | USEPA National Ambient Water Quality Criterion for dacthal (DCPA) of 0.008 µg/L.
Guideline Reference: | Compilation of Water Quality Goals - 2007 for toxicity data
Spatial Representation: | Water samples were collected from Orestimba Creek at River Road near Crows Landing.
Temporal Representation: | Water samples were collected from January 2000 to September 2005 at variable intervals (e.g. hourly, daily, weekly, twice per month).
Environmental Conditions: |
QAPP Information: | Data Quality: Good: U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1-A9, available online at http://pubs.water.usgs.gov/twri9A
QAPP Information Reference(s): | National field manual for the collection of water quality data. Reston, VA. U.S. Geological Survey. Office of Water Quality
| Field measurements: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6. In United States Geological Survey (USGS). Variously dated. National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1-A9, available online at http://pubs.water.usgs.gov/twri9A.

DECISION ID | 13218
Pollutant: | Dieldrin
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 2 samples exceed the narrative toxicity objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13218

LOE ID: | 22891
Pollutant: | Dieldrin
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: | 2
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Two (2) water samples were collected from Orestimba Creek, Highway 33, above Kilburn between July 2006 and August 2006 by the Westside San Joaquin River Water Quality Coalition group. All the water samples exceeded the CTR criteria for Dieldrin of 0.00014 µg/L.
Data Reference:
Water Quality Objective/Criterion: | - Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007a)Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000):Criteria based on Human Health Protection (30-day average) with a Dieldrin limit of less than 0.00014 µg/L for water and fish consumption.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Two (2) water samples were collected from Orestimba Creek, Highway 33, above Kilburn July 2006 and August 2006 by the Westside San Joaquin River Water Quality Coalition group (Stanislaus County), California.
Temporal Representation: | - The Westside San Joaquin River Water Quality Coalition group collected samples between July 2006 and August 2006 at monthly intervals.
Environmental Conditions: |
QAPP Information: | In accordance with section 6.1.4 of the Listing Policy, data from major monitoring programs in California and Published USGS reports are considered of adequate quality.
QAPP Information Reference(s):

DECISION ID | 14394
Pollutant: | Dimethoate
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Twenty-one of 100 water samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the 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. Twenty-one of 100 water samples exceed the Evaluation Guideline value for dimethoate (0.2 ug/L, which is one-tenth the 96-hour LC50 for the most sensitive freshwater species, Cyclops strenuus, a copepod crustacean), and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 14394

LOE ID: | 26111
Pollutant: | Dimethoate
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 22
Number of Exceedances: | 8
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Twenty-two water samples were collected from Orestimba Creek, under the Irrigated Lands Regulatory Program, between July 2004 and August 2006. Eight of the 22 water samples contained dimethoate at concentrations that exceeded the Evaluation Guideline value of 0.2 µg/L.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. Where valid testing has developed 96 hour LC50 values for aquatic organisms (the concentration that kills one half of the test organisms in 96 hours), 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. Other available technical information on the pesticide (such as Lowest Observed Effect Concentrations and No Observed Effect Levels), the water bodies and the organisms involved will be evaluated to determine if lower concentrations are required to meet the narrative objectives (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | The one-tenth of 96-hour LC50 value, tested with dimethoate on the most sensitive species in freshwater (Cyclops strenuus, a copepod crustacean), is 0.2 µg/L.
Guideline Reference: | Ecotoxicity database. U.S. Environmental Protection Agency, Office of Pesticide Programs
Spatial Representation: | Water samples were collected from Orestimba Creek at Kilburn Road and at River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek every other week or monthly between July 2004 and August 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826 ) requirements.
QAPP Information Reference(s): | Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
LOE ID: | 26113
Pollutant: | Dimethoate
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 74
Number of Exceedances: | 13
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Seventy-four water samples were collected from Orestimba Creek between January 2000 February 2005, as reported in the DPR Surface Water Database. Thirteen of the 74 water samples exceeded the Evaluation Guideline of 0.2 µg/L.
Data Reference: | Surface Water database (SWDB) for Central Valley waterbodies, 2000-2005
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Where valid testing has developed 96 hour LC50 values for aquatic organisms (the concentration that kills one half of the test organisms in 96 hours), 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. Other available technical information on the pesticide (such as Lowest Observed Effect Concentrations and No Observed Effect Levels), the water bodies and the organisms involved will be evaluated to determine if lower concentrations are required to meet the narrative objectives. The one-tenth of 96-hour LC50 value for dimethoate for the most sensitive species in freshwater (Cyclops strenuus, a copepod crustacean), is 0.2 µg/L.
Guideline Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| ECOTOX database, aquatic data. U. S. Environmental Protection Agency
Spatial Representation: | Water samples were collected from Orestimba Creek at River Road.
Temporal Representation: | Water samples were collected from Orestimba Creek daily, weekly, or monthly between January 2000 and February 2005.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. Minimum requirements for the Surface Water Database are: Name of the sampling agency or organization Date that each sample was collected Date of each sample analysis County where samples were taken Detailed sampling location information (including latitude and longitude or township/range/section if available), detailed map or description of each sampling site (i.e., address, cross roads, etc.) Name or description of water body sampled Name of the active ingredient analyzed for; concentration detected (with unit of measurement), and limit of quantitation Description of analytical QA/QC plan, or statement that no formal plan exists Additional optional requirements are included on DPRs webpage at http://www.cdpr.ca.gov/docs/emon/surfwtr/caps/req.htm.
QAPP Information Reference(s):
LOE ID: | 26115
Pollutant: | Dimethoate
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 Asses Water Quality: | Four water samples were collected from Orestimba Creek under the Pesticide TMDL program, in January to March 2006. None of the samples exceeded the Evaluation Guideline of 0.2 ug/L. 0 of 2 available concentrations exceeded the criterion (0.2 µg/L).
Data Reference: | Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports
Water Quality Objective/Criterion: | No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Where valid testing has developed 96 hour LC50 values for aquatic organisms (the concentration that kills one half of the test organisms in 96 hours), 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. Other available technical information on the pesticide (such as Lowest Observed Effect Concentrations and No Observed Effect Levels), the water bodies and the organisms involved will be evaluated to determine if lower concentrations are required to meet the narrative objectives. The one-tenth of 96-hour LC50 value for dimethoate for the most sensitive species in freshwater (Cyclops strenuus, a copepod crustacean), is 0.2 µg/L.
Guideline Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| ECOTOX database, aquatic data. U. S. Environmental Protection Agency
Spatial Representation: | Water samples were collected from Orestimba Creek at Kilburn Road.
Temporal Representation: | Water samples were collected from Orestimba Creek on 14 and 15 January 2006, on 28 February 2006, and on 1 March 2006.
Environmental Conditions: |
QAPP Information: | Data Quality: Good. All sampling, analysis and QA/QC protocols are described in a QAPP prepared for the Pesticide TMDL program sampling.
QAPP Information Reference(s):

DECISION ID | 12568
Pollutant: | Escherichia coli (E. Coli)
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Source Unknown
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Fifty-nine of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Fifty-nine of 101 samples exceed the E. Coli objective and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12568

LOE ID: | 22912
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 30
Number of Exceedances: | 22
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | The Westside San Joaquin River Water Quality Coalition collected 30 samples from July 2004 to October 2006. Twenty-two out of the 30 samples collected exceeded the evaluation objective.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | The USEPA E. Coli objective of 235/100 mL in any single sample (USEPA 1986).
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Samples were collected at Orestimba Creek at Highway 33.
Temporal Representation: | Sampling occurred July 2004 to October 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 22913
Pollutant: | Escherichia coli (E. Coli)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 71
Number of Exceedances: | 37
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | The Central Valley Regional Water Quality Control Board Surface Water Ambient Monitoring Program collected 71 samples from November 2004 to November 2005. Thirty-seven out of 71 samples exceeded the evaluation objective.
Data Reference: | Monitoring Data from the Surface Water Ambient Monitoring Program (SWAMP), San Joaquin River Basin - 2007 Data Review
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
| Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Evaluation Guideline: | The USEPA E. Coli objective of 235/100 mL in any single sample (USEPA 1986).
Guideline Reference: | Ambient Water Quality Criteria for Bacteria - 1986. EPA440/5-84-002
Spatial Representation: | Samples were collected at four locations: Orestimba Creek at Anderson Road, Orestimba creek at Bell Road, Orestimba Creek at Highway 33, and Orestimba Creek at Orestimba Road.
Temporal Representation: | Sampling occurred from November 2004 to November 2005.
Environmental Conditions: |
QAPP Information: | Data quality: Good. Monitoring was conducted in accordance with the State Water Resources Control Board's Quality Assurance Program Plan for the State of California's Surface Water Ambient Monitoring Program.
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 12560
Pollutant: | Sediment Toxicity
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One lines of evidence are available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 2 samples exceed the narrative toxicity objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12560

LOE ID: | 22934
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Sediment
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 2
Data and Information Type: | TOXICITY TESTING
Data Used to Asses Water Quality: | Two of the 2 samples tested with Hyalella azteca were toxic and violated the narrative toxicity objective. Two samples collected at Highway 33 exhibited a statistically significant decrease in survival compared to the control. The sample dates and percent of control (in parentheses) are as follows:13 September 2004 (57)11 September 2006 (6)
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
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. (CVRWQCB, 2007)
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 10-day Hyalella azteca sediment toxicity tests.
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33.
Temporal Representation: | The samples were taken in September 2004 and September 2006
Environmental Conditions: |
QAPP Information: | Data quality: Excellent. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 12561
Pollutant: | Unknown Toxicity
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Agriculture
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Six of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Six of 16 samples tested with ceriodaphnia exceed the narrative toxicity objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. In addition, 0 of 17 samples tested with fathead minnow exceed the narrative toxicity objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. Lastly, 0 of 16 samples tested with selenastrum exceed the narrative toxicity 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.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12561

LOE ID: | 22937
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Asses Water Quality: | Zero of 16 samples tested with Selenastrum capricornutum were toxic and violated the narrative toxicity objective.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
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.¿ (CVRWQCB, 2007)
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 4-day chronic-style toxicity tests.
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33
Temporal Representation: | Samples were collected from July 2004 to August 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Excellent. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 22935
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 19
Number of Exceedances: | 6
Data and Information Type: | TOXICITY TESTING
Data Used to Asses Water Quality: | 6 of the 19 samples tested with Ceriodaphnia dubia were toxic and violated the narrative toxicity objective. Six samples collected at Highway 33 exhibited a statistically significant decrease in survival compared to the control. The sample dates and percent of control (in parentheses) are as follows:06 July 2004 (0)16 February 2005 (74)09 August 2005 (0)16 August 2005 (0)11 July 2006 (0)17 July 2006 (0)
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
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.¿ (CVRWQCB, 2007)
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 4-day acute-style toxicity tests.
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33
Temporal Representation: | Samples were collected from July 2004 ¿ August 2006
Environmental Conditions: |
QAPP Information: | Data quality: Excellent. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):
LOE ID: | 22936
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 14
Number of Exceedances: | 0
Data and Information Type: | TOXICITY TESTING
Data Used to Asses Water Quality: | Zero of the 14 samples tested with Pimephales promelas were toxic and violated the narrative toxicity objective.
Data Reference: | Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program
| Monitoring and Reporting Program, Order Nos. R5-2003-0826, R5-2005-0833, and R5-2008-0005 for Coalition Groups Under Resolution No. R5-2003-0105, Conditional Waiver of Waste Discharge Requirements for Discharges From Irrigated Lands Within the Central Valley Region
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.¿ (CVRWQCB, 2007)
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 4-day acute-style toxicity tests.
Guideline Reference:
Spatial Representation: | Samples were collected from Orestimba Creek at Highway 33
Temporal Representation: | Samples were collected from July 2004 to August 2006.
Environmental Conditions: |
QAPP Information: | Data quality: Excellent. Monitoring was conducted in accordance with Central Valley Water Board Monitoring and Reporting Program (order number R5-2003-0826) requirements (CVRWQCB, 2003)
QAPP Information Reference(s):

DECISION ID | 5148
Pollutant: | Chlorpyrifos
Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)(2006)
Revision Status | Original
Sources: | Agriculture
Expected TMDL Completion Date: | 2008
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under section 4.1 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. One of the samples exceeded the pesticide water quality objective but the number of samples is insufficient to determine with the confidence and power required by the Listing Policy. Based on the readily available data and information, the weight of evidence indicates that there is insufficient justification in favor of removing this water segment-pollutant combination from the 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. One of 14 samples exceeded the CDFG Hazard Assessment Criteria. At least 28 samples are needed before a pollutant can be considered for removal from the list using the frequencies presented in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.
SWRCB Board Decision / Staff Recommendation: | This is a decision made by the State Water Resources Control Board and approved by the USEPA in 2006 . No new data were assessed by the Regional Board for 2008. The decision has not changed.
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 5148

LOE ID: | 2794
Pollutant: | Chlorpyrifos
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Wildlife Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Chlorpyrifos was detected at concentrations exceeding toxicity benchmarks. Chlorpyrifos was detected in one sample at 0.0705 µg/L, and found at trace concentrations in one additional sample. The detection exceeds both the acute and chronic CDFG WQC (Starner et al., 2003).
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Pesticide concentrations shall not exceed those allowable by applicable antidegradation policies (see State Water Resources Control Board Resolution No. 68-16 and 40 CFR section 131.12). No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. Discharges shall not result in pesticide concentrations in bottom sediments or aquatic life that adversely affect beneficial uses. 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. Pesticide concentrations shall not exceed the lowest levels technically and economically achievable. Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of pesticides in excess of the Maximum Contaminant Levels set forth in California Code of Regulations, Title 22, Division 4, Chapter 15.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: | CDFG Hazard Assessment Criteria - 14 ng/L 4-day average and 25 ng/L 1-hour average.
Guideline Reference: | Placeholder reference 2006 303(d)
Spatial Representation: | Samples were taken on Orestimba Creek at River Road.
Temporal Representation: | Sampling began on July 2, 2002, and continued throughout the summer until September 30, 2002. Each site was sampled once per week.
Environmental Conditions: | At each sampling event, temperature, dissolved oxygen (DO), pH, and electrical conductivity (EC) were measured in situ at each sampling site. DO, EC and temperature were measured. The pH at Orestimba Creek ranged from 7.1 to 7.8. Measured water temperature ranged from 16 to 25.4 ºC. DO and EC had ranges of 6.21 to 8.28 mg/L and 641 to 887 µS/cm, respectively.
QAPP Information: | Quality Control (QC) for the chemical analysis portion of this study was conducted in accordance with Standard Operating Procedure QAQC001.00 (Segawa, 1995).
QAPP Information Reference(s):

DECISION ID | 4949
Pollutant: | Diazinon
Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)(2006)
Revision Status | Original
Sources: | Agriculture
Expected TMDL Completion Date: | 2008
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under section 4.1 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. One of the samples exceeded the water quality objective but the number of samples is insufficient to determine with the confidence and power required by the Listing Policy. Based on the readily available data and information, the weight of evidence indicates that there is insufficient justification in favor of removing this water segment-pollutant combination from the 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. One of 14 samples exceeded the pesticide water quality objective. At least 28 samples are needed before a pollutant can be considered for removal from the list using the frequencies presented in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The Regional Board will update this decision when new data and information become available and are assessed.
SWRCB Board Decision / Staff Recommendation: | This is a decision made by the State Water Resources Control Board and approved by the USEPA in 2006 . No new data were assessed by the Regional Board for 2008. The decision has not changed.
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 4949

LOE ID: | 2795
Pollutant: | Diazinon
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Wildlife Habitat
Number of Samples: | 14
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Diazinon was detected at concentrations exceeding toxicity benchmarks. Of the 14 samples collected at Orestimba Creek, diazinon was detected three times (21% detection frequency), with concentrations of 0.043, 0.046, and 0.276 µg/L. The two lowest detected concentrations were below the CDFG chronic WQC of 0.10 µg/L. The 0.276 µg/L detection exceeded both the chronic and the acute WQC. The three samples with quantifiable diazinon detections were taken from consecutive sampling events at Orestimba Creek on 8/5, 8/12-10 - and 8/19/2002 (Starner et al., 2003).
Data Reference: | Placeholder reference 2006 303(d)
Water Quality Objective/Criterion: | Pesticide concentrations shall not exceed those allowable by applicable antidegradation policies (see State Water Resources Control Board Resolution No. 68-16 and 40 CFC section 131.12). No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. Discharges shall not result in pesticide concentrations in bottom sediments or aquatic life that adversely affect beneficial uses. 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. Pesticide concentrations shall not exceed the lowest levels technically and economically achievable. Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of pesticides in excess of the Maximum Contaminant Levels set forth in California Code of Regulations, Title 22, Division 4, Chapter 15.
Objective/Criterion Reference: | Placeholder reference 2006 303(d)
Evaluation Guideline: | CDFG Hazard Assessment Criteria - 0.10 ug/L 4-day average and 0.16 ug/L 1-hour average. (Siepman & Finlayson, 2000; Finlayson, 2004).
Guideline Reference: | Placeholder reference 2006 303(d)
Spatial Representation: | Samples were taken on Orestimba Creek at River Road.
Temporal Representation: | Sampling began on July 2, 2002, and continued throughout the summer until September 30, 2002. Each site was sampled once per week.
Environmental Conditions: | At each sampling event, temperature, dissolved oxygen (DO), pH, and electrical conductivity (EC) were measured in situ at each sampling site. DO, EC and temperature were measured. The pH at Orestimba Creek ranged from 7.1 to 7.8. Measured water temperature ranged from 16 to 25.4 ºC. DO and EC had ranges of 6.21 to 8.28 mg/L and 641 to 887 µS/cm, respectively.
QAPP Information: | Quality Control (QC) for the chemical analysis portion of this study was conducted in accordance with Standard Operating Procedure QAQC001.00 (Segawa, 1995).
QAPP Information Reference(s):

DECISION ID | 7105
Pollutant: | Azinphos-methyl (Guthion)
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2006)
Revision Status | Original
Sources: | Agriculture
Expected TMDL Completion Date: | 2008
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.
RWQCB Board Decision / Staff Recommendation: | No new data were assessed for 2008. The decision has not changed.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 7105

LOE ID: | 4498
Pollutant: | Azinphos-methyl (Guthion)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Not Recorded
Beneficial Use: | Warm Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Asses Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: | Placeholder reference pre-2006 303(d)
Water Quality Objective/Criterion: | Unspecified
Objective/Criterion Reference: | Placeholder reference pre-2006 303(d)
Evaluation Guideline: | Unspecified
Guideline Reference: | Placeholder reference pre-2006 303(d)
Spatial Representation: | Unspecified
Temporal Representation: | Unspecified
Environmental Conditions: | Unspecified
QAPP Information: | Unspecified
QAPP Information Reference(s):