Final California 2010 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name:	Duck Slough (Merced County)
Water Body ID:	CAR5357000020080808202452
Water Body Type:	River & Stream


DECISION ID	14568	Region 5
Duck Slough (Merced County)

Pollutant:	Bifenthrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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 22 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14568, Bifenthrin	Region 5
Duck Slough (Merced County)

LOE ID:

22066

Pollutant:

Bifenthrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

23 water samples were collected from Duck Slough from July 2004 through September 2006 representing 22 concentrations. 1 of 22 concentrations exceeded the maximum value (0.00093 ug/L). 1 sample had concentrations less than the quantitation limits and the quantitation limit is greater than the water quality criterion concentration. Therefore, the sample was not used in this analysis in accordance with section 6.1.5.5 of the Listing Policy

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses (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:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

The Board will use the best available technicalinformation to evaluate compliance with the narrative objectives. - the Board will consider one tenth of 96 hour LC50 for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life (CRWQCB, 2006). The one tenth of 96 hour LC50 tested on the most sensitive species in freshwater is 0.00093 ug/L (ECOTOX, 2008).

Guideline Reference:

Ecotox database

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road and Arboleda Drive.

Temporal Representation:

Samples were collected at various intervals (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	14618	Region 5
Duck Slough (Merced County)

Pollutant:	Dimethoate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the 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 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 10 water samples exceed the Evaluation Guideline of 0.2 ug/L (based on the one-tenth LC50 for the most sensitive species in freshwater (Cyclops strenuus, a copepod crustacean), and 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14618, Dimethoate	Region 5
Duck Slough (Merced County)

LOE ID:

26139

Pollutant:

Dimethoate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Eighteen water samples were collected from three sites on Duck Slough, under the Irrigated Lands Reporting Program, from two sites, between July 2004 and July 2006.
One of the 18 water samples exceeded the Evaluation Guideline of 0.2 ug/L.

Data Reference:

Zipped file of Central Valley Waterways Pesticide TMDL monitoring data spreadsheets and reports

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. 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:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

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 ug/L.

Guideline Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

ECOTOX database, aquatic data. U. S. Environmental Protection Agency

Spatial Representation:

Samples were collected from Duck Slough at Arboleda Drive, Gurr Road, and Highway 99.

Temporal Representation:

Water samples were collected from Duck Slough at Gurr Road on 31 July 2004, and monthly between 17 May 2006 and 13 September 2006. Water samples were collected from Duck Slough at Hughway 99 monthly between 17 May 2006 and 13 September 2006. Water samples were collected from Duck Slough at Arboleda Drive on 20 July 2004, 4 and 18 August 2004, 1 and 15 September 2004, and 1 and 4 February 2005.

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	14569	Region 5
Duck Slough (Merced County)

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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. 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 49 samples fell below the minimum criterion water quality objective listed in the Sacramento/San Joaquin River Basin Plan and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14569, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

22039

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Forty-nine samples were taken from Duck Slough between 2004 and 2006. None of the forty-nine samples fell below the Water Quality Objective for minimum dissolved oxygen content in surface water.

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

From the Sacramento/San Joaquin River Basin Plan the (WARM) Warm Freshwater Habitat criterion is a Minimum Dissolved Oxygen content of 5mg/L

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road, Highway 99 and Arboleda Drive in Merced County.

Temporal Representation:

Samples were collected between July 2004 and September 2006. Samples were collected at bi-monthly and 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	14567	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	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. 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 54 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14567, Salinity	Region 5
Duck Slough (Merced County)

LOE ID:

22046

Pollutant:

Salinity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Twenty-three samples were taken from Duck Slough between 2004 and 2006. One of the twenty-three samples exceeds 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

SWAMP Data:

Non-SWAMP

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:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from Duck Slough at Arboleda Drive, Gurr Road and Highway 99 in Merced County.

Temporal Representation:

Samples were collected between July 2004 and September 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):

Line of Evidence (LOE) for Decision ID 14567, Salinity	Region 5
Duck Slough (Merced County)

LOE ID:

22045

Pollutant:

Salinity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Thirty-one samples were taken from Duck Slough 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

SWAMP Data:

Non-SWAMP

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:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from Duck Slough at Arboleda Road, Gurr Road and Highway 99 in Merced County.

Temporal Representation:

Samples were collected between July 2004 and September 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	14570	Region 5
Duck Slough (Merced County)

Pollutant:	Thiobencarb/Bolero
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the 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 15 samples exceeded the concentration criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14570, Thiobencarb/Bolero	Region 5
Duck Slough (Merced County)

LOE ID:

22055

Pollutant:

Thiobencarb/Bolero

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

15 water samples were collected from Duck Slough from July 2004 through September 2006, representing 15 concentrations. 0 of 15 concentrations exceeded Secondary MCL concentration of 1 ug/L.

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Evaluation Guideline:

Secondary Maximum Contaminate Levels (MCLs) for drinking water standard adopted by the California Department of Public Health (CDPH) is 1 ug/L (CDPH, 2008).

Guideline Reference:

California Code of Regulations, Title 22, Division 4, Chapter 15. Domestic Water Quality and Monitoring

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road, Highway 99, and Arboleda Drive.

Temporal Representation:

Samples were collected at monthly interval 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	14571	Region 5
Duck Slough (Merced County)

Pollutant:	pH (high)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One 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 49 samples had pH values higher than 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):

Line of Evidence (LOE) for Decision ID 14571, pH (high)	Region 5
Duck Slough (Merced County)

LOE ID:

22040

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The East San Joaquin Water Quality Coalition collected 49 samples from July 2004 to September 2006. Three of the 49 samples did not meet the evaluation objective and had a pH higher than 8.5.

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

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. Measurement of pH within the range of 6.5 and 8.5. A high pH value is greater than 8.5

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected from Duck Slough at three locations: Gurr Road, Highway 99, and Arboleda Drive.

Temporal Representation:

Sampling occurred from July 2004 to 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	13011	Region 5
Duck Slough (Merced County)

Pollutant:	Chlorpyrifos
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

Regional Board Conclusion:	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. Three samples exceed the narrative toxicity 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. Three of twenty-one available calculated 4-day average chlorpyrifos concentrations exceeded the 4-day average chlorpyrifos criterion, and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Three of the twenty-one available 1-hour average chlorpyrifos concentrations exceeded the 1-hour average chlorpyrifos criterion, and this exceeds the allowable frequency listed in Table 3.1 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 13011, Chlorpyrifos	Region 5
Duck Slough (Merced County)

LOE ID:

22038

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Twenty-one water samples were collected from Duck Slough between July 2004 and September 2006, representing twenty-one calculated 4-day average chlorpyrifos concentrations and twenty-one 1-hour average chlorpyrifos concentrations. Three of the twenty-one 4-day average chlorpyrifos concentrations exceeded the 4-day average chlorpyrifos criterion of 0.015 ug/L. Three of the twenty-one 1-hour average chlorpyrifos concentrations exceeded the 1-hour average chlorpyrifos criterion of 0.025 ug/L.

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

California Department of Fish and Game Hazard Assessment Chlorpyrifos Criteria: 0.015 ug/L as a 4-day average concentration, and 0.025 ug/L as a 1-hour average concentration, not to be exceeded more than once every three years.

Guideline Reference:

Water quality criteria for diazinon and chlorpyrifos. Administrative Report 00-3. Rancho Cordova, CA: Pesticide Investigations Unit, Office of Spills and Response. CA Department of Fish and Game

Spatial Representation:

Samples were collected from Duck Slough at Highway 99 and at Arboleda Drive.

Temporal Representation:

Samples were collected at monthly from July 2004 through September 2006.

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	13006	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	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. One lines of evidence are available in the administrative record to assess this pollutant. Sixteen 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. Sixteen of 31 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 13006, Escherichia coli (E. coli)	Region 5
Duck Slough (Merced County)

LOE ID:

22056

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The East San Joaquin Water Quality Coalition collected 31 samples from July 2004 to September 2006. Sixteen out of 31 samples exceeded the evaluation objective.

Data Reference:

Monitoring Data from the Surface Water Ambient Monitoring Program (SWAMP), San Joaquin River Basin - 2007 Data Review

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

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 two locations: Duck Slough at Gurr Road and Duck Slough at Highway 99.

Temporal Representation:

Sampling occurred from July 2004 to September 2006.

Environmental Conditions:

QAPP Information:

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	13004	Region 5
Duck Slough (Merced County)

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:	Source Unknown
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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. 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 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. Three of 10 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 13004, Sediment Toxicity	Region 5
Duck Slough (Merced County)

LOE ID:

22048

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Three of the 10 samples tested with Hyalella azteca were toxic and violated the narrative toxicity objective. Three samples collected at Gurr Road exhibited a statistically significant decrease in survival compared to the control. The sample dates and percent of control (in parentheses) are as follows:31 August 2004 (36)12 July 2005 (65)20 September 2005 (4)

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. 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:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Statistically significant difference from control using a t-test with 10-day Hyalella azteca sediment toxicity tests.

Guideline Reference:

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition. U.S. Environmental Protection Agency Office of Research and Development, Duluth, MI , U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-600/R-99/064

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road, Hwy 99 and Arboleda Drive.

Temporal Representation:

Samples were collected from August 2004 to August 2006.

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	13003	Region 5
Duck Slough (Merced County)

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:	Source Unknown
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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. Ten 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 37 samples tested with selenastrum exceed the narrative toxicity objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. In addition, 4 of 40 samples tested with ceriodaphnia 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.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.

USEPA Action (if applicable):	USEPA approved the listing of this water body as a water quality limited segment requiring a TMDL for this pollutant.

Line of Evidence (LOE) for Decision ID 13003, Unknown Toxicity	Region 5
Duck Slough (Merced County)

LOE ID:

22047

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

4 of the 40 samples tested with Ceriodaphnia dubia were toxic and violated the narrative toxicity objective. Three samples collected at Gurr Road exhibited a statistically significant decrease in survival compared to the control. The sample dates and percent of control (in parentheses) are as follows:28 February 2006 (37)10 March 2006 (35)15 March 2006 (42)One sample collected at Highway 99 exhibited a statistically significant decrease in survival compared to the control. The sample date and percent of control (in parentheses) are as follows:17 May 2006 (0)

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Statistically significant difference from control using a t-test with 4-day acute-style toxicity tests.

Guideline Reference:

Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fifth Edition. U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-821-R-02-012

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road and Highway 99.

Temporal Representation:

Samples were collected from July 2004 to September 2006.

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):

Line of Evidence (LOE) for Decision ID 13003, Unknown Toxicity	Region 5
Duck Slough (Merced County)

LOE ID:

22041

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

None of the 37 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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Statistically significant difference from control using a t-test with 4-day acute-style toxicity tests.

Guideline Reference:

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road and Highway 99.

Temporal Representation:

Samples were collected from July 2004 - September 2006

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):

Line of Evidence (LOE) for Decision ID 13003, Unknown Toxicity	Region 5
Duck Slough (Merced County)

LOE ID:

22042

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm Freshwater Habitat

Aquatic Life Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

Six of 37 samples tested with Selenastrum capricornutum were toxic and violated the narrative toxicity objective. One sample collected at Gurr Road exhibited a statistically significant decrease in growth compared to the control. The sample date and percent of control (in parentheses) are as follows:24 September 2004 (74)One sample collected at Hwy 99 exhibited a statistically significant decrease in growth compared to the control. The sample date and percent of control (in parentheses) are as follows:12 July 2005 (77)Four samples collected at Arboledo Drive exhibited a statistically significant decrease in growth compared to the control. The sample dates and percent of control (in parentheses) are as follows:20 July 2004 (86)4 August 2004 (60)18 August 2004 (79)15 September 2004 (62)

Data Reference:

Revised Draft of the 2007 Review of the Monitoring Data for the Irrigated Lands Regulatory Conditional Waiver Program

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed

Evaluation Guideline:

Statistically significant difference from control using a t-test with 4-day chronic-style toxicity tests.

Guideline Reference:

Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fourth Edition. U.S. Environmental Protection Agency Office of Water, Washington, DC EPA-821-R-02-013

Spatial Representation:

Samples were collected from Duck Slough at Gurr Road, Hwy 99 and Arboledo Drive.

Temporal Representation:

Samples were collected from July 2004 to September 2006.

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):