Draft California 2026 Integrated Report (303(d) List/305(b) Report)

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Data for this waterbody was collected over the date range 2018-05-08 to 2018-08-14

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159518, Bifenthrin	Region 5
Duck Slough (Merced County)

LOE ID:

330845

Pollutant:

Bifenthrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 6 of the 7 samples exceeded the water quality threshold for Bifenthrin. Although a total of 15 samples were collected, 8 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for bifenthrin is 0.1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of bifenthrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

The samples were collected between the dates of 2019-04-16 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159518, Bifenthrin	Region 5
Duck Slough (Merced County)

LOE ID:

352981

Pollutant:

Bifenthrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 8 samples were collected, 8 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2007-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159518, Bifenthrin	Region 5
Duck Slough (Merced County)

LOE ID:

352976

Pollutant:

Bifenthrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Bifenthrin. Although a total of 18 samples were collected, 18 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	159515	Region 5
Duck Slough (Merced County)

Pollutant:	2, 4 DB / 4-(2,4-dichlorophenoxy) butyric acid
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159515, 2, 4 DB / 4-(2,4-dichlorophenoxy) butyric acid	Region 5
Duck Slough (Merced County)

LOE ID:

331398

Pollutant:

2, 4 DB / 4-(2,4-dichlorophenoxy) butyric acid

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Dichlorophenoxybutyric Acid, 2,4-.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for 2, 4 DB / 4-(2,4-dichlorophenoxy) butyric acid is the USEPA Aquatic Life Benchmark of 83 ug/L for a vascular plant (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-11-07 and 2019-03-08

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	171202	Region 5
Duck Slough (Merced County)

Pollutant:	Alachlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171202, Alachlor	Region 5
Duck Slough (Merced County)

LOE ID:

63194

Pollutant:

Alachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

A total of 6 individual whole water samples were collected; 0 of 6 samples exceeded the objective (2 ug/L).

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for alachlor is 2 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):


DECISION ID	118612	Region 5
Duck Slough (Merced County)

Pollutant:	Aldicarb
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant for Municipal and Domestic Supply (MUN) and Warm Freshwater Habitat (WARM). Zero of the thirty samples exceed the evaluation criteria for MUN and zero of the seventy-two samples exceed the evaluation criteria for WARM. LOE 63195 has been replaced by LOE 221717 and LOE 221564 due to a reassessment of data using a U.S. EPA aquatic life benchmark. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the thirty samples exceed the evaluation criteria for MUN and zero of the seventy-two samples exceed the evaluation criteria for WARM and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118612, Aldicarb	Region 5
Duck Slough (Merced County)

LOE ID:

186026

Pollutant:

Aldicarb

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 30 samples exceeded the water quality threshold for Aldicarb.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for aldicarb incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 3 ug/L

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118612, Aldicarb	Region 5
Duck Slough (Merced County)

LOE ID:

185952

Pollutant:

Aldicarb

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Water Quality Control Plan for the Sacramento and San Joaquin River Basins).

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Aldicarb is the USEPA Aquatic Life Benchmark of 0.46 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118612, Aldicarb	Region 5
Duck Slough (Merced County)

LOE ID:

221717

Pollutant:

Aldicarb

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 21 samples exceeded the water quality threshold for Aldicarb.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Aldicarb is the USEPA Aquatic Life Benchmark of 0.46 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118612, Aldicarb	Region 5
Duck Slough (Merced County)

LOE ID:

221564

Pollutant:

Aldicarb

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Aldicarb is the USEPA Aquatic Life Benchmark of 0.46 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):


DECISION ID	164856	Region 5
Duck Slough (Merced County)

Pollutant:	Aldrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164856, Aldrin	Region 5
Duck Slough (Merced County)

LOE ID:

186057

Pollutant:

Aldrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 9 samples exceeded the water quality threshold for Aldrin.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The established numeric criteria for aldrin to protect aquatic life in freshwater as an instantaneous maximum concentration is 3 ug/L . This established criteria was divided by 2 in order to better represent a CMC value as specified in footnote (g) of Table (b)(1) of the California Toxics Rule, 2000.

Objective/Criterion Reference:

Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164856, Aldrin	Region 5
Duck Slough (Merced County)

LOE ID:

186159

Pollutant:

Aldrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Aldrin. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Aldrin criteria for the protection of human health from the consumption of water and organisms is 0.00013 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	167313	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 167313, Ammonia	Region 5
Duck Slough (Merced County)

LOE ID:

330733

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for Ammonia as N.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Total Ammonia criterion continuous concentration (expressed as a 30-day average) to protect aquatic life in freshwater is Temperature and pH dependent, and was calculated according to the formula listed in the Aquatic Life Ambient Water Quality Criteria for Ammonia Freshwater 2013 document.

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-11-07 and 2019-09-10

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	118562	Region 5
Duck Slough (Merced County)

Pollutant:	Arsenic
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant for the Warm Freshwater Habitat (WARM) and Municipal and Domestic Supply (MUN) beneficial uses. Zero of the fifty-six samples exceed the criteria for WARM and three of the fifty-six samples exceed the objective for MUN. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the fifty-six samples exceed the evaluation criteria for WARM and three of the fifty-six samples exceed the evaluation criteria for MUN and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118562, Arsenic	Region 5
Duck Slough (Merced County)

LOE ID:

63196

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 37 samples exceed the criterion for Arsenic.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for arsenic is 0.010 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-4/21/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118562, Arsenic	Region 5
Duck Slough (Merced County)

LOE ID:

186216

Pollutant:

Arsenic

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 3 of 19 samples exceeded the water quality threshold for Arsenic.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for arsenic incorporated by reference in the Basin Plan is 0.010 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2016-08-09

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118562, Arsenic	Region 5
Duck Slough (Merced County)

LOE ID:

186415

Pollutant:

Arsenic

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 19 samples exceeded the water quality threshold for Arsenic.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater for dissolved arsenic is 150 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2016-08-09

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118562, Arsenic	Region 5
Duck Slough (Merced County)

LOE ID:

63197

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 37 samples exceed the criterion for Arsenic.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater for dissolved arsenic is 0.150 mg/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-4/21/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	171193	Region 5
Duck Slough (Merced County)

Pollutant:	Atrazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). LOE 63210 has been replaced by LOE 221388 and LOE 221655 due to a reassessment of data using a U.S. EPA aquatic life benchmark. The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

221655

Pollutant:

Atrazine

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of <1 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

221388

Pollutant:

Atrazine

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of <1 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

186505

Pollutant:

Atrazine

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 28 samples exceeded the water quality threshold for Atrazine.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of <1 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

63209

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Atrazine.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for atrazine is 1 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

63208

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

A total of 6 individual whole water samples were collected; 0 of 6 samples exceeded the objective (1 ug/L).

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for atrazine is 0.001 mg/L (Title 22 of the California Code of Regulations ).

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171193, Atrazine	Region 5
Duck Slough (Merced County)

LOE ID:

186398

Pollutant:

Atrazine

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for atrazine incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.001 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118580	Region 5
Duck Slough (Merced County)

Pollutant:	Azinphos-methyl (Guthion)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of zero samples exceed the evaluation guideline for the protection of freshwater aquatic life WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of zero samples exceed the evaluation guideline for the protection of freshwater aquatic life WARM and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118580, Azinphos-methyl (Guthion)	Region 5
Duck Slough (Merced County)

LOE ID:

186427

Pollutant:

Azinphos-methyl (Guthion)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Azinphos Methyl. Although a total of 28 samples were collected, 28 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria for azinphos methyl for freshwater aquatic life protection is 0.01 ug/l (instantaneous maximum)

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118580, Azinphos-methyl (Guthion)	Region 5
Duck Slough (Merced County)

LOE ID:

63211

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Azinphos methyl. Forty samples were not used in the assessment because the laboratory data reporting limit was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)

Objective/Criterion Reference:

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

Evaluation Guideline:

The National Recommended Water Quality criterion for Azinphos Methyl (Guthion) for the protection of freshwater aquatic life is a maximum of 0.01 ug/l.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118564	Region 5
Duck Slough (Merced County)

Pollutant:	Boron
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant for Agricultural Supply. Zero of the 52 samples, reported as a total concentration or with the fraction not reported, exceed the guideline for Agricultural Supply. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 52 samples, reported as a total concentration or with the fraction not reported, exceed the guideline for Agricultural Supply and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118564, Boron	Region 5
Duck Slough (Merced County)

LOE ID:

186548

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 14 samples exceeded the water quality threshold for Boron.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water, including irrigation of various types of crops and stock watering. At or below the limits presented in the Water Quality Goals tables, agricultural uses of water should not be limited. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The criteria for boron is 700 ug/L (0.7 mg/L).

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118564, Boron	Region 5
Duck Slough (Merced County)

LOE ID:

79590

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff assessed ILRP data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 38 samples exceed the criterion for Boron.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [ Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):


DECISION ID	118565	Region 5
Duck Slough (Merced County)

Pollutant:	Cadmium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess this pollutant. Two LOEs are available for the WARM beneficial use and three LOEs are available for the MUN beneficial use. Zero of the 57 samples exceed the water quality objective for MUN, and zero of the 17 samples exceed the criteria for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 57 samples exceed the water quality objective for MUN, and zero of the 17 samples exceed the criteria for WARM and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118565, Cadmium	Region 5
Duck Slough (Merced County)

LOE ID:

63221

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed AgWaiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Cadmium.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The cadmium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for the metals criterion.

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [ Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 12/16/2008-4/21/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118565, Cadmium	Region 5
Duck Slough (Merced County)

LOE ID:

186837

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 12 samples exceeded the water quality threshold for Cadmium.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for cadmium incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.005 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118565, Cadmium	Region 5
Duck Slough (Merced County)

LOE ID:

186698

Pollutant:

Cadmium

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for Cadmium.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for cadmium incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.005 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2011-08-16

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118565, Cadmium	Region 5
Duck Slough (Merced County)

LOE ID:

63220

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 37 samples exceed the criterion for Cadmium.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for cadmium is 5 ug/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-4/21/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118565, Cadmium	Region 5
Duck Slough (Merced County)

LOE ID:

186699

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Toxics Rule (CTR) lists criterion continuous concentrations to protect aquatic life in freshwater. The criterion in freshwater is hardness dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness dependent formula for the metals criterion.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159506	Region 5
Duck Slough (Merced County)

Pollutant:	Carbaryl
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two line of evidence is available in the administrative record to assess this pollutant. Zero of the 63 samples exceed the evaluation guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 63 samples exceed the evaluation guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159506, Carbaryl	Region 5
Duck Slough (Merced County)

LOE ID:

330911

Pollutant:

Carbaryl

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Carbaryl.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The USEPA recommended water quality criterion for freshwater aquatic life for carbaryl is 2.1 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-05-14 and 2019-05-14

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159506, Carbaryl	Region 5
Duck Slough (Merced County)

LOE ID:

187127

Pollutant:

Carbaryl

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The USEPA recommended water quality criteria for freshwater aquatic life for carbaryl is 2.1 µg/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159506, Carbaryl	Region 5
Duck Slough (Merced County)

LOE ID:

63222

Pollutant:

Carbaryl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Carbaryl.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The USEPA recommended water quality criterion for freshwater aquatic life for carbaryl is 2.1 µg/L.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118567	Region 5
Duck Slough (Merced County)

Pollutant:	Carbofuran
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Zero of the 77 samples exceed the objective for MUN. Zero of 77 samples exceed the evaluation guideline for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 77 samples exceed the objective for MUN. Zero of 77 samples exceed the evaluation guideline for WARM. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118567, Carbofuran	Region 5
Duck Slough (Merced County)

LOE ID:

63229

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 46 samples exceed the criterion for Carbofuran.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

No individual pesticide or combination of pesticides shall be present in concentrations that adversely affect beneficial uses. (Water Quality Control Plan, Central Valley Region, Tulare Lake Basin)

Objective/Criterion Reference:

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

Evaluation Guideline:

The freshwater criterion maximum concentration for carbofuran is 0.5 µg/L (DFG 92-3, 1992).

Guideline Reference:

Hazard Assessment of the Insecticide Carbofuran to Aquatic Organisms in the Sacramento River System

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-7/20/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118567, Carbofuran	Region 5
Duck Slough (Merced County)

LOE ID:

63230

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 46 samples exceed the criterion for Carbofuran.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Carbofuran is 18 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-7/20/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118567, Carbofuran	Region 5
Duck Slough (Merced County)

LOE ID:

187138

Pollutant:

Carbofuran

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 31 samples exceeded the water quality threshold for Carbofuran.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The interim water quality criterion for the protection of sensitive aquatic organisms from Carbofuran is 0.5 ug/l (DFG 92-3, 1992).

Guideline Reference:

Hazard Assessment of the Insecticide Carbofuran to Aquatic Organisms in the Sacramento River System

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118567, Carbofuran	Region 5
Duck Slough (Merced County)

LOE ID:

186926

Pollutant:

Carbofuran

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Carbofuran incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.018 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164846	Region 5
Duck Slough (Merced County)

Pollutant:	Chlordane
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164846, Chlordane	Region 5
Duck Slough (Merced County)

LOE ID:

186964

Pollutant:

Chlordane

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlordane. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The Chlordane criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0043 ug/L (California Toxics Rule, 2000).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164846, Chlordane	Region 5
Duck Slough (Merced County)

LOE ID:

186913

Pollutant:

Chlordane

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chlordane. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Chlordane criterion for the protection of human health from the consumption of water and organisms is 0.00057 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159530	Region 5
Duck Slough (Merced County)

Pollutant:	Chloropicrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159530, Chloropicrin	Region 5
Duck Slough (Merced County)

LOE ID:

187343

Pollutant:

Chloropicrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chloropicrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Chloropicrin is the USEPA Aquatic Life Benchmark of 5.5 ug/L for a fish (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2018-06-12 to 2018-06-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159530, Chloropicrin	Region 5
Duck Slough (Merced County)

LOE ID:

330951

Pollutant:

Chloropicrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Chloropicrin. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for chloropicrin is the USEPA Aquatic Life Benchmark of 5.5 ug/L for a fish (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-06-11 and 2019-06-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	159507	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159507, Chlorothalonil	Region 5
Duck Slough (Merced County)

LOE ID:

330983

Pollutant:

Chlorothalonil

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for Chlorothalonil.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for chlorothalonil is the USEPA Aquatic Life Benchmark of 0.6 ug/L for an invertebrate (chronic).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-03-08 and 2019-08-13

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	159508	Region 5
Duck Slough (Merced County)

Pollutant:	Copper
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOE 187772, 187923, 187737, 187855, and 63231 have been replaced by LOE 346298 and 346300 due to a reassessment of data using The California Secondary Maximum Contaminant Level. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

346298

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary Maximum Contaminant Level for copper incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 1.0 mg/L assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2011-11-08 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

346300

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

331087

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-06-11 and 2019-06-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

331119

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved copper criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 9 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-04-16 and 2019-06-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

187901

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

63232

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed AgWaiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 15 samples exceed the criterion for Copper.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Toxics Rule (CTR) lists criterion continuous concentrations (4-day average) to protect aquatic life in freshwater. The chromium criterion in freshwater is hardness-dependent for each sample and varies based on the ambient hardness during sampling. Section (b)(1) in CTR contains the hardness-dependent formula for metals criteria.

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [ Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 12/16/2008-6/15/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159508, Copper	Region 5
Duck Slough (Merced County)

LOE ID:

187633

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118610	Region 5
Duck Slough (Merced County)

Pollutant:	Cyanazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant for Warm Freshwater Habitat. Zero of the 60 samples, reported as a total concentration or with the fraction not reported, exceed the guideline for Warm Freshwater Habitat. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 60 samples, reported as a total concentration or with the fraction not reported, exceed the guideline for Warm Freshwater Habitat and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118610, Cyanazine	Region 5
Duck Slough (Merced County)

LOE ID:

63233

Pollutant:

Cyanazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Cyanazine.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The EC50 for Navicula pelliculosa (freshwater diatom) for cyanazine is 4.8 ug/L (USEPA Office of Pesticide Programs Ecotoxicity database).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118610, Cyanazine	Region 5
Duck Slough (Merced County)

LOE ID:

187849

Pollutant:

Cyanazine

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for cyanazine is the EC50 of 4.8 ug/L for Navicula pelliculosa (freshwater diatom) (USEPA Office of Pesticide Programs Ecotoxicity database).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	159523	Region 5
Duck Slough (Merced County)

Pollutant:	Cyfluthrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159523, Cyfluthrin	Region 5
Duck Slough (Merced County)

LOE ID:

352986

Pollutant:

Cyfluthrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 17 samples were collected, 17 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for cyfluthrin is 0.2 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of cyfluthrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Cyfluthrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159523, Cyfluthrin	Region 5
Duck Slough (Merced County)

LOE ID:

187768

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for Cyfluthrin is 0.2 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Cyfluthrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2018-03-05 to 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159523, Cyfluthrin	Region 5
Duck Slough (Merced County)

LOE ID:

196179

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin, total. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for cyfluthrin, 0.11 ug/g, is one-tenth of the median lethal concentration (LC50; 1.1 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.1 ug/g is the geometric mean of LC50 values for cyfluthrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Date for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159523, Cyfluthrin	Region 5
Duck Slough (Merced County)

LOE ID:

352987

Pollutant:

Cyfluthrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cyfluthrin. Although a total of 8 samples were collected, 8 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Cyfluthrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2007-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159523, Cyfluthrin	Region 5
Duck Slough (Merced County)

LOE ID:

331137

Pollutant:

Cyfluthrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Cyfluthrin. Although a total of 15 samples were collected, 14 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Cyfluthrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	159524	Region 5
Duck Slough (Merced County)

Pollutant:	Cyhalothrin, Lambda
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159524, Cyhalothrin, Lambda	Region 5
Duck Slough (Merced County)

LOE ID:

190837

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Lambda-cyhalothrin. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for Lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Lambda-cyhalothrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2018-03-05 to 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159524, Cyhalothrin, Lambda	Region 5
Duck Slough (Merced County)

LOE ID:

196217

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for lambda-cyhalothrin, 0.044 ug/g, is one-tenth of the median lethal concentration (LC50; 0.44 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.44 ug/g is the geometric mean of LC50 values for lambda-cyhalothrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Data for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159524, Cyhalothrin, Lambda	Region 5
Duck Slough (Merced County)

LOE ID:

331679

Pollutant:

Cyhalothrin, Lambda

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Lambda-cyhalothrin. Although a total of 17 samples were collected, 16 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for lambda-cyhalothrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Lambda-cyhalothrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Lambda-cyhalothrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159524, Cyhalothrin, Lambda	Region 5
Duck Slough (Merced County)

LOE ID:

214899

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Cyhalothrin, lambda. Twenty-five samples were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Lambda-cyhalothrin

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	159519	Region 5
Duck Slough (Merced County)

Pollutant:	Cypermethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2024)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159519, Cypermethrin	Region 5
Duck Slough (Merced County)

LOE ID:

353001

Pollutant:

Cypermethrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 17 samples were collected, 17 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for cypermethrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Cypermethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159519, Cypermethrin	Region 5
Duck Slough (Merced County)

LOE ID:

188042

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Cypermethrin. Although a total of 3 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for Cypermethrin is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Cypermethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Data for this waterbody was collected over the date range 2017-10-10 to 2018-08-14

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159519, Cypermethrin	Region 5
Duck Slough (Merced County)

LOE ID:

331183

Pollutant:

Cypermethrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 15 samples were collected, 15 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-10-09 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159519, Cypermethrin	Region 5
Duck Slough (Merced County)

LOE ID:

353012

Pollutant:

Cypermethrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin. Although a total of 8 samples were collected, 8 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2007-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159519, Cypermethrin	Region 5
Duck Slough (Merced County)

LOE ID:

291390

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Cypermethrin, Total. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for cypermethrin, 0.03 ug/g, is one-tenth of the median lethal concentration (LC50; 0.3 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.3 ug/g is the geometric mean of LC50 values for cypermethrin from Maund et al. (2002).

Guideline Reference:

Partitioning, bioavailability, and toxicity of the pyrethroid insecticide cypermethrin in sediments. Environmental Toxicology and Chemistry 21:9-15

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Date for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159531	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159531, Cyprodinil	Region 5
Duck Slough (Merced County)

LOE ID:

331209

Pollutant:

Cyprodinil

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for cyprodinil is the USEPA Aquatic Life Benchmark of 8.2 ug/L for an invertebrate (chronic).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2019-02-06

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	168427	Region 5
Duck Slough (Merced County)

Pollutant:	DDD (Dichlorodiphenyldichloroethane)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 168427, DDD (Dichlorodiphenyldichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

188116

Pollutant:

DDD (Dichlorodiphenyldichloroethane)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDD(p,p'). Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDD(p,p) criteria for the protection of human health from the consumption of water and organisms is 0.00059 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 168427, DDD (Dichlorodiphenyldichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

78791

Pollutant:

DDD (Dichlorodiphenyldichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The DDD method detection limit for all 32 samples collected from Duck Slough (Merced County) are greater than the criterion; therefore, the data could not be assessed with the accuracy required by the Listing Policy

Data Reference:

Data for Metals and Nutrients for the City of Anderson, 2006-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Sacramento/San Joaquin River Basin Plan (CVRWQCB, 2007) Pesticides: Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer.- California Toxics Rule Criteria (USEPA, 2000), for Inland Surface Waters based on drinking water and aquatic organism consumption. The criteria are based on human health protection for carcinogenicity at 1-in-a-million risk level (30-day average) with a limit of 0.00083 ug/L for DDD

Objective/Criterion Reference:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Thirty two water samples were collected from two monitoring sites on Duck Slough (Merced County) [Duck Slough @ Gurr Rd - 535XDSAGR; Duck Slough @ Hwy 99 - 535XDSAHN]. Each sample was analyzed for DDD(p,p').

Temporal Representation:

The samples were collected at both monitoring sites approximately monthly between 2/12/2007 and 9/18/2007 and between 1/25/2008 and 9/30/2008

Environmental Conditions:

QAPP Information:

The data was collected under the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):


DECISION ID	169089	Region 5
Duck Slough (Merced County)

Pollutant:	DDE (Dichlorodiphenyldichloroethylene)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 169089, DDE (Dichlorodiphenyldichloroethylene)	Region 5
Duck Slough (Merced County)

LOE ID:

78872

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The DDE method detection limit for all 32 samples collected from Duck Slough (Merced County) are greater than the criterion; therefore, the data could not be assessed with the accuracy required by the Listing Policy

Data Reference:

Data for Metals and Nutrients for the City of Anderson, 2006-2008.

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Temporal Representation:

The samples were collected at both monitoring sites approximately monthly between 2/12/2007 and 9/18/2007 and between 1/25/2008 and 9/30/2008

Environmental Conditions:

QAPP Information:

The data was collected under the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 169089, DDE (Dichlorodiphenyldichloroethylene)	Region 5
Duck Slough (Merced County)

LOE ID:

188036

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDE(p,p'). Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDE(p,p) criteria for the protection of human health from the consumption of water and organisms is 0.00059 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	169179	Region 5
Duck Slough (Merced County)

Pollutant:	DDT (Dichlorodiphenyltrichloroethane)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 169179, DDT (Dichlorodiphenyltrichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

63250

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for DDT(p,p). Thirty samples were not used in the assessment because the laboratory data reporting limit was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 169179, DDT (Dichlorodiphenyltrichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

188296

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT(p,p) criteria for the protection of human health from the consumption of water and organisms is 0.00059 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 169179, DDT (Dichlorodiphenyltrichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

188298

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for DDT(p,p'). Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDT criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 169179, DDT (Dichlorodiphenyltrichloroethane)	Region 5
Duck Slough (Merced County)

LOE ID:

63243

Pollutant:

DDT (Dichlorodiphenyltrichloroethane)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The criterion for total DDT to protect human health from consumption of water and organisms is 0.00059 ug/L (California Toxics Rule).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118618	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118618, Deltamethrin	Region 5
Duck Slough (Merced County)

LOE ID:

196482

Pollutant:

Deltamethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for deltamethrin, 0.079 ug/g, is one-tenth of the median lethal concentration (LC50; 0.79 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.79 ug/g is the geometric mean of LC50 values for deltamethrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Data for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118621	Region 5
Duck Slough (Merced County)

Pollutant:	Demeton
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:	Pollution

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118621, Demeton	Region 5
Duck Slough (Merced County)

LOE ID:

188554

Pollutant:

Demeton

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The USEPA Recommended freshwater eaquatic life criteria for demeton is 0.1 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118572	Region 5
Duck Slough (Merced County)

Pollutant:	Diazinon
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 69 samples exceed the evaluation guideline for the WARM beneficial use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 69 samples exceed the evaluation guideline for the WARM beneficial use and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118572, Diazinon	Region 5
Duck Slough (Merced County)

LOE ID:

63251

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 40 samples exceed the criterion for Diazinon.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The freshwater chronic criterion value for diazinon is 0.1 ug/L, expressed as a continuous concentration (Finlayson, 2004).

Guideline Reference:

Water quality for diazinon. Memorandum to J. Karkoski, Central Valley RWQCB. Rancho Cordova, CA: Pesticide Investigation Unit, CA Department of Fish and Game

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118572, Diazinon	Region 5
Duck Slough (Merced County)

LOE ID:

188489

Pollutant:

Diazinon

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 29 samples exceeded the water quality threshold for Diazinon.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The freshwater chronic value for diazinon is 0.1 ug/L (4 day average)(Finlayson, 2004).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2018-09-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118573	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118573, Dichlorvos	Region 5
Duck Slough (Merced County)

LOE ID:

188828

Pollutant:

Dichlorvos

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Dichlorvos. Although a total of 28 samples were collected, 28 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dichlorvos is the USEPA Aquatic Life Benchmark of 0.0058 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	118574	Region 5
Duck Slough (Merced County)

Pollutant:	Dicofol
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the fifty-one samples exceed the evaluation guideline. LOE 63252 has been replaced by LOE 221479 and LOE 221503 due to a reassessment of data using a U.S. EPA aquatic life benchmark. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the fifty-one samples exceed the evaluation guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118574, Dicofol	Region 5
Duck Slough (Merced County)

LOE ID:

221479

Pollutant:

Dicofol

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dicofol is the USEPA Aquatic Life Benchmark of 4.4 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118574, Dicofol	Region 5
Duck Slough (Merced County)

LOE ID:

221503

Pollutant:

Dicofol

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dicofol is the USEPA Aquatic Life Benchmark of 4.4 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118574, Dicofol	Region 5
Duck Slough (Merced County)

LOE ID:

188695

Pollutant:

Dicofol

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dicofol is the USEPA Aquatic Life Benchmark of 4.4 ug/L for a fish (chronic).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	164848	Region 5
Duck Slough (Merced County)

Pollutant:	Dieldrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 164848, Dieldrin	Region 5
Duck Slough (Merced County)

LOE ID:

63254

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Dieldrin.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 164848, Dieldrin	Region 5
Duck Slough (Merced County)

LOE ID:

188897

Pollutant:

Dieldrin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164848, Dieldrin	Region 5
Duck Slough (Merced County)

LOE ID:

188899

Pollutant:

Dieldrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Dieldrin. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Dieldrin criteria for the protection of human health from the consumption of water and organisms is 0.00014 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164848, Dieldrin	Region 5
Duck Slough (Merced County)

LOE ID:

63253

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Dieldrin. Sixteen samples were not used in the assessment because the laboratory data reporting limit was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The criterion for Dieldrin to protect human health from the consumption of water and organisms is 0.00014 ug/L (California Toxics Rule).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	159520	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:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollution

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Five lines of evidence are available in the administrative record to assess this pollutant. Two of the 79 samples exceed the evaluation guideline for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of the 79 samples exceed the evaluation guideline for WARM and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159520, Dimethoate	Region 5
Duck Slough (Merced County)

LOE ID:

221462

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 22 samples exceeded the water quality threshold for Dimethoate.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159520, Dimethoate	Region 5
Duck Slough (Merced County)

LOE ID:

189186

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159520, Dimethoate	Region 5
Duck Slough (Merced County)

LOE ID:

221438

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 2 of 28 samples exceeded the water quality threshold for Dimethoate.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2009-05-19

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159520, Dimethoate	Region 5
Duck Slough (Merced County)

LOE ID:

331435

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for dimethoate is the USEPA Aquatic Life Benchmark of 0.5 ug/L for an invertebrate (chronic).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2019-02-06

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	118576	Region 5
Duck Slough (Merced County)

Pollutant:	Disulfoton
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence is available in the administrative record to assess this pollutant. Zero of six samples exceed the evaluation guideline for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. 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 six samples exceed the evaluation guideline for WARM and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	This decision was completed by SWRCB staff.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118576, Disulfoton	Region 5
Duck Slough (Merced County)

LOE ID:

63263

Pollutant:

Disulfoton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Disulfoton.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The USEPA National Recommended Water Quality criterion for disulfoton in freshwater (0.05 ug/L) is an aquatic life maximum (instantaneous) level.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118576, Disulfoton	Region 5
Duck Slough (Merced County)

LOE ID:

189111

Pollutant:

Disulfoton

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Disulfoton. Although a total of 28 samples were collected, 28 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for disulfoton is the USEPA Aquatic Life Benchmark of 0.01 ug/L for chronic toxicity in invertebrates (7 day average).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	171194	Region 5
Duck Slough (Merced County)

Pollutant:	Diuron
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Three lines of evidence are available in the administrative record to assess this pollutant for Warm Freshwater Habitat. One of 62 samples, reported as a total concentration, exceed the guideline for Warm Freshwater Habitat. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 62 samples, reported as a total concentration, exceed the guideline for Warm Freshwater Habitat and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171194, Diuron	Region 5
Duck Slough (Merced County)

LOE ID:

353030

Pollutant:

Diuron

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 16 samples exceeded the water quality threshold for Diuron.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 171194, Diuron	Region 5
Duck Slough (Merced County)

LOE ID:

188925

Pollutant:

Diuron

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 171194, Diuron	Region 5
Duck Slough (Merced County)

LOE ID:

353045

Pollutant:

Diuron

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 1 of 16 samples exceeded the water quality threshold for Diuron.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of diuron does not exceed 1.3 ug/L (UC Davis Aquatic Life Criteria).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: III. Diuron. Reviews of Environmental Contamination and Toxicology 216:105-141.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	171205	Region 5
Duck Slough (Merced County)

Pollutant:	Dodine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171205, Dodine	Region 5
Duck Slough (Merced County)

LOE ID:

353047

Pollutant:

Dodine

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for dodine is the USEPA Aquatic Life Benchmark of 0.08 ug/L for nonvascular plants.

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-04-09 and 2018-04-09

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	164849	Region 5
Duck Slough (Merced County)

Pollutant:	Endrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 164849, Endrin	Region 5
Duck Slough (Merced County)

LOE ID:

63272

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Endrin.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Endrin criterion for the protection of human health from the consumption of water and organisms is 0.76 ug/L. (California Toxics Rule, 2000)

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 164849, Endrin	Region 5
Duck Slough (Merced County)

LOE ID:

63273

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Endrin.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L. (California Toxics Rule, 2000)

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 164849, Endrin	Region 5
Duck Slough (Merced County)

LOE ID:

189578

Pollutant:

Endrin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Endrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.036 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164849, Endrin	Region 5
Duck Slough (Merced County)

LOE ID:

189500

Pollutant:

Endrin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Endrin criteria for the protection of human health from the consumption of water and organisms is 0.76 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159526	Region 5
Duck Slough (Merced County)

Pollutant:	Esfenvalerate/Fenvalerate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Line of evidence #63275 was replaced by #214913. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the 25 samples exceed the evaluation guideline for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 25 samples exceed the evaluation guideline for WARM and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159526, Esfenvalerate/Fenvalerate	Region 5
Duck Slough (Merced County)

LOE ID:

189935

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Water Quality Criteria Report for Esfenvalerate

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2018-06-12 to 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159526, Esfenvalerate/Fenvalerate	Region 5
Duck Slough (Merced County)

LOE ID:

214913

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 25 samples exceed the criterion for Esfenvalerate/Fenvalerate.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for Esfenvalerate is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Esfenvalerate were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used. The evaluation guideline for fenvalerate, 0.113 ug/L, is one-tenth of the median lethal concentration (LC50 = 1.13 ug/L) as determined in a 96 hour toxicity test using the fathead minnow, Pimephales promelas. (USEPA OPP Ecotoxicity database)

Guideline Reference:

Water Quality Criteria Report for Esfenvalerate

Guideline Reference:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159526, Esfenvalerate/Fenvalerate	Region 5
Duck Slough (Merced County)

LOE ID:

331519

Pollutant:

Esfenvalerate/Fenvalerate

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Esfenvalerate. Although a total of 14 samples were collected, 14 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for esfenvalerate is 0.3 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Esfenvalerate were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Esfenvalerate

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-07-09 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	159525	Region 5
Duck Slough (Merced County)

Pollutant:	Fenpropathrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollution

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159525, Fenpropathrin	Region 5
Duck Slough (Merced County)

LOE ID:

353061

Pollutant:

Fenpropathrin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-05-08 and 2018-09-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159525, Fenpropathrin	Region 5
Duck Slough (Merced County)

LOE ID:

331561

Pollutant:

Fenpropathrin

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Fenpropathrin is the USEPA Aquatic Life Benchmark of 0.0015 ug/L for an invertebrate (chronic).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-05-14 and 2020-08-12

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159525, Fenpropathrin	Region 5
Duck Slough (Merced County)

LOE ID:

196446

Pollutant:

Fenpropathrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the evaluation guideline for Fenpropathrin. Although a total of 2 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for fenpropathrin, 0.1 ug/g, is one-tenth of the median lethal concentration (LC50; 1 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1 ug/g is the geometric mean of LC50 values for fenpropathrin from Ding et al. ( 2011).

Guideline Reference:

Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca. Arch. Environ. Contam. Toxicol. 61:83¿92.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Data for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118627	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118627, Flumioxazin	Region 5
Duck Slough (Merced County)

LOE ID:

189651

Pollutant:

Flumioxazin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Flumioxazin is the USEPA Aquatic Life Benchmark of 0.49 ug/L for a vascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2017-11-07 and 2017-11-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	159509	Region 5
Duck Slough (Merced County)

Pollutant:	Glyphosate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

331593

Pollutant:

Glyphosate

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-06-11 and 2019-06-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

63282

Pollutant:

Glyphosate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

A total of 6 individual whole water samples were collected; 0 of 6 samples exceeded the evaluation guideline (700 ug/L).

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Glyphosate is 700 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

63283

Pollutant:

Glyphosate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Glyphosate.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Glyphosate is 700 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

190239

Pollutant:

Glyphosate

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Glyphosate incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.7 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

190241

Pollutant:

Glyphosate

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

221749

Pollutant:

Glyphosate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

221766

Pollutant:

Glyphosate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Glyphosate is the USEPA Aquatic Life Benchmark of 11900 ug/L for a vascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159509, Glyphosate	Region 5
Duck Slough (Merced County)

LOE ID:

331607

Pollutant:

Glyphosate

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Glyphosate incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.7 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-06-11 and 2019-06-11

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	164850	Region 5
Duck Slough (Merced County)

Pollutant:	Heptachlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164850, Heptachlor	Region 5
Duck Slough (Merced County)

LOE ID:

190615

Pollutant:

Heptachlor

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Heptachlor criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164850, Heptachlor	Region 5
Duck Slough (Merced County)

LOE ID:

190509

Pollutant:

Heptachlor

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Heptachlor criteria for the protection of human health from the consumption of water and organisms is 0.00021 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164851	Region 5
Duck Slough (Merced County)

Pollutant:	Heptachlor epoxide
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164851, Heptachlor epoxide	Region 5
Duck Slough (Merced County)

LOE ID:

190520

Pollutant:

Heptachlor epoxide

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Heptachlor Epoxide criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.0038 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164851, Heptachlor epoxide	Region 5
Duck Slough (Merced County)

LOE ID:

190500

Pollutant:

Heptachlor epoxide

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Heptachlor Epoxide. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Heptachlor Epoxide criteria for the protection of human health from the consumption of water and organisms is 0.0001 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164858	Region 5
Duck Slough (Merced County)

Pollutant:	Hexachlorocyclohexane (HCH), alpha
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164858, Hexachlorocyclohexane (HCH), alpha	Region 5
Duck Slough (Merced County)

LOE ID:

190080

Pollutant:

Hexachlorocyclohexane (HCH), alpha

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for HCH, alpha-. Although a total of 9 samples were collected, 9 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The alpha-HCH (alpha-BHC) criteria for the protection of human health from consumption of water and organisms is 0.0039 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164857	Region 5
Duck Slough (Merced County)

Pollutant:	Hexachlorocyclohexane (HCH), beta
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164857, Hexachlorocyclohexane (HCH), beta	Region 5
Duck Slough (Merced County)

LOE ID:

190181

Pollutant:

Hexachlorocyclohexane (HCH), beta

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The BHC, beta criteria for the protection of human health from the consumption of water and organisms is 0.014 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159516	Region 5
Duck Slough (Merced County)

Pollutant:	Imidacloprid
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159516, Imidacloprid	Region 5
Duck Slough (Merced County)

LOE ID:

331658

Pollutant:

Imidacloprid

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 2 samples were collected, 2 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the 4-day average concentration of imidacloprid does not exceed 0.016 ug/L.

Guideline Reference:

Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-04-16 and 2019-05-14

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159516, Imidacloprid	Region 5
Duck Slough (Merced County)

LOE ID:

190696

Pollutant:

Imidacloprid

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Imidacloprid. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of Imidacloprid does not exceed 0.016 ug/L. (UC Davis Water Quality Criteria)

Guideline Reference:

Water Quality Criteria Report for Imidacloprid Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology. University of California, Davis

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2018-04-09 to 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118583	Region 5
Duck Slough (Merced County)

Pollutant:	Lead
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Six lines of evidence are available in the administrative record to assess this pollutant. Zero of the 36 samples exceed the objective for Municipal & Domestic Supply in the dissolved fraction and zero of the 23 samples exceed the objective for Municipal & Domestic Supply in the total fraction. Zero of five samples exceed the Criteria for Warm Freshwater Habitat in the dissolved fraction and zero of five samples exceed Warm Freshwater Habitat in the unknown fraction. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 36 samples exceed the objective for Municipal & Domestic Supply in the dissolved fraction and zero of the 23 samples exceed the objective for Municipal & Domestic Supply in the total fraction. Zero of five samples exceed the Criteria for Warm Freshwater Habitat in the dissolved fraction and zero of five samples exceed Warm Freshwater Habitat in the unknown fraction. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

63284

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed AgWaiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Lead.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [ Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 12/16/2008-4/21/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

190805

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: At a minimum, water designated for use as MUN shall not contain lead in excess of 0.015 mg/l.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2011-04-19 and 2011-09-13

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

190654

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: At a minimum, water designated for use as MUN shall not contain lead in excess of 0.015 mg/l.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2018-03-05

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

190653

Pollutant:

Lead

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: At a minimum, water designated for use as MUN shall not contain lead in excess of 0.015 mg/l.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2011-04-19 and 2011-09-13

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

191050

Pollutant:

Lead

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and the results are as follows: 0 of the 5 samples exceeded the water quality threshold for Lead. Although a total of 6 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN).

Temporal Representation:

Data for this waterbody was collected over the date range 2011-04-19 to 2011-09-13

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118583, Lead	Region 5
Duck Slough (Merced County)

LOE ID:

190936

Pollutant:

Lead

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 17 samples exceeded the water quality threshold for Lead.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: At a minimum, water designated for use as MUN shall not contain lead in excess of 0.015 mg/l.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-04-08

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164852	Region 5
Duck Slough (Merced County)

Pollutant:	Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 164852, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 5
Duck Slough (Merced County)

LOE ID:

190118

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The gamma-BHC (Lindane) criterion maximum concentration to protect aquatic life in freshwater is 0.95 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164852, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 5
Duck Slough (Merced County)

LOE ID:

190324

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The BHC, gamma(Lindane) criteria for the protection of human health from the consumption of water and organisms is 0.019 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	118585	Region 5
Duck Slough (Merced County)

Pollutant:	Linuron
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. LOE 63285 has been replaced by LOE 222069 and LOE 222006 due to a reassessment of data using a U.S. EPA aquatic life benchmark

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118585, Linuron	Region 5
Duck Slough (Merced County)

LOE ID:

222069

Pollutant:

Linuron

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Linuron. Although a total of 21 samples were collected, 21 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN).

Temporal Representation:

Date for this waterbody was collected over the date range 2006-05-17 to 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118585, Linuron	Region 5
Duck Slough (Merced County)

LOE ID:

190994

Pollutant:

Linuron

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Linuron. Although a total of 30 samples were collected, 30 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118585, Linuron	Region 5
Duck Slough (Merced County)

LOE ID:

222006

Pollutant:

Linuron

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Linuron. Although a total of 21 samples were collected, 21 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2006-05-17 to 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):


DECISION ID	118607	Region 5
Duck Slough (Merced County)

Pollutant:	Methidathion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. LOE 63293 has been replaced by LOEs 221845 and 222010 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118607, Methidathion	Region 5
Duck Slough (Merced County)

LOE ID:

222010

Pollutant:

Methidathion

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 28 samples exceeded the water quality threshold for Methidathion.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methidathion is the USEPA Aquatic Life Benchmark of 0.66 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2009-05-19

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118607, Methidathion	Region 5
Duck Slough (Merced County)

LOE ID:

221845

Pollutant:

Methidathion

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methidathion is the USEPA Aquatic Life Benchmark of 0.66 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118607, Methidathion	Region 5
Duck Slough (Merced County)

LOE ID:

191457

Pollutant:

Methidathion

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methidathion is the USEPA Aquatic Life Benchmark of 0.66 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	118602	Region 5
Duck Slough (Merced County)

Pollutant:	Methiocarb
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. LOE 63294 has been replaced by LOE 221951 and 221972 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118602, Methiocarb	Region 5
Duck Slough (Merced County)

LOE ID:

221951

Pollutant:

Methiocarb

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methiocarb is the USEPA Aquatic Life Benchmark of 2.75 ug/L for a invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118602, Methiocarb	Region 5
Duck Slough (Merced County)

LOE ID:

221972

Pollutant:

Methiocarb

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methiocarb is the USEPA Aquatic Life Benchmark of 2.75 ug/L for a invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118602, Methiocarb	Region 5
Duck Slough (Merced County)

LOE ID:

191357

Pollutant:

Methiocarb

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Methiocarb is the USEPA Aquatic Life Benchmark of 2.75 ug/L for a invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	118603	Region 5
Duck Slough (Merced County)

Pollutant:	Methomyl
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Zero of the 62 samples exceed the evaluation guideline for Warm Freshwater Habitat. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 62 samples exceed the evaluation guideline for Warm Freshwater Habitat and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118603, Methomyl	Region 5
Duck Slough (Merced County)

LOE ID:

63295

Pollutant:

Methomyl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Methomyl.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The Basin Plan states: "Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide..." The criteria continuous concentration for Methomyl in the San Joaquin River system is 0.5 ug/L (4-day average). (CDFG, 1996)

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118603, Methomyl	Region 5
Duck Slough (Merced County)

LOE ID:

191318

Pollutant:

Methomyl

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The Basin Plan states: \Where valid testing has developed 96-hour LC50 values for aquatic organisms..., the Board will consider one tenth of this value for the most sensitive species tested as the upper limit (daily maximum) for the protection of aquatic life... or [O]ther available information on the pesticide...\" The criteria continuous concentration for Methomyl in the San Joaquin River system is 0.5 ug/L (4-day average). "

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	118587	Region 5
Duck Slough (Merced County)

Pollutant:	Methoxychlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Zero of 41 samples exceed the California Primary MCL for MUN, and 0 of 41 samples exceed the criteria for WARM. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four lines of evidence are available in the administrative record to assess this pollutant. Zero of 41 samples exceed the California Primary MCL for MUN, and 0 of 41 samples exceed the criteria for WARM and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118587, Methoxychlor	Region 5
Duck Slough (Merced County)

LOE ID:

191447

Pollutant:

Methoxychlor

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The USEPA National Recommended Water Quality Criteria toxicity threshold for methoxychlor for freshwater aquatic life protection is 0.03 ug/l.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118587, Methoxychlor	Region 5
Duck Slough (Merced County)

LOE ID:

191533

Pollutant:

Methoxychlor

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Methoxychlor incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.03 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118587, Methoxychlor	Region 5
Duck Slough (Merced County)

LOE ID:

63305

Pollutant:

Methoxychlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Methoxychlor.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Total identifiable persistent chlorinated hydrocarbon pesticides shall not be present in the water column at concentrations detectable within the accuracy of analytical methods approved by the Environmental Protection Agency or the Executive Officer (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118587, Methoxychlor	Region 5
Duck Slough (Merced County)

LOE ID:

63304

Pollutant:

Methoxychlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Methoxychlor.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Methoxychlor, 30 ug/L, is incorporated by reference into the (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118588	Region 5
Duck Slough (Merced County)

Pollutant:	Methyl Parathion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Zero of zero samples exceed the water quality objective (California Department of Fish and Game instantaneous aquatic life criterion) for MUN. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of zero samples exceed the water quality objective (California Department of Fish and Game instantaneous aquatic life criterion) for MUN and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to Section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118588, Methyl Parathion	Region 5
Duck Slough (Merced County)

LOE ID:

192949

Pollutant:

Methyl Parathion

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Parathion, Methyl. Although a total of 28 samples were collected, 28 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The California Department of Fish and Game instantaneous aquatic life criterion for Methyl Parathion is 0.08 ug/L.

Guideline Reference:

Hazard Assessment of the Insecticide Methyl Parathion to Aquatic Organisms in the Sacramento River System. California Department of Fish and Game. Environmental Services Division. Administrative Report 92-1

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118588, Methyl Parathion	Region 5
Duck Slough (Merced County)

LOE ID:

63306

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 0 samples exceed the criterion for Parathion, Methyl. Forty samples were not used in the assessment because the laboratory data reporting limit(s) was above the objective and therefore the results could not be quantified with the level of certainty required by the Listing Policy.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

The California Department of Fish and Game instantaneous aquatic life criterion for Methyl Parathion is 0.08 ug/L.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	171200	Region 5
Duck Slough (Merced County)

Pollutant:	Metolachlor
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171200, Metolachlor	Region 5
Duck Slough (Merced County)

LOE ID:

63308

Pollutant:

Metolachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Metolachlor.

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

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:

The National Ambient Water Quality criterion for Human Health and Welfare Protection of Public Health Effects (other than cancer effects) from Water & Fish Consumption for metolachlor is 44 µg/L.

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):


DECISION ID	171196	Region 5
Duck Slough (Merced County)

Pollutant:	Molinate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. LOE 63152 has been replaced by LOE 221848 and 221851 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171196, Molinate	Region 5
Duck Slough (Merced County)

LOE ID:

63154

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 34 samples exceed the criterion for Molinate.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Molinate is 20 ug/L .

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 171196, Molinate	Region 5
Duck Slough (Merced County)

LOE ID:

63153

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Molinate.

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Molinate is 20 ug/L .

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171196, Molinate	Region 5
Duck Slough (Merced County)

LOE ID:

221848

Pollutant:

Molinate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The California Department of Fish and Wildlife hazard assessment instantaneous criterion (1-hour average) for the protection of aquatic life for Molinate is 13 ug/L.

Guideline Reference:

Hazard Assessment of the Rice Herbicides Molinate and Thiobencarb to Aquatic Organisms in the Sacramento River System. Administrative Report 90-1. California Department of Fish and Game, Environmental Services Division

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 171196, Molinate	Region 5
Duck Slough (Merced County)

LOE ID:

221851

Pollutant:

Molinate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The California Department of Fish and Wildlife hazard assessment instantaneous criterion (1-hour average) for the protection of aquatic life for Molinate is 13 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118589	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	This decision was made by SWRCB staff.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118589, Molybdenum	Region 5
Duck Slough (Merced County)

LOE ID:

191860

Pollutant:

Molybdenum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. A 10 ug/L criteria is the recommended maximum concentration of molybdenum in irrigation water.

Guideline Reference:

Water Quality for Agriculture, Food and Agriculture Organization of the United Nations - Irrigation and Drainage Paper No. 29, Rev 1, Rome (1985)

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	164853	Region 5
Duck Slough (Merced County)

Pollutant:	Nickel
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 164853, Nickel	Region 5
Duck Slough (Merced County)

LOE ID:

63161

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 38 samples exceed the criterion for Nickel.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for nickel is 0.1 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 164853, Nickel	Region 5
Duck Slough (Merced County)

LOE ID:

63162

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed AgWaiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Nickel.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [ Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 12/16/2008-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 164853, Nickel	Region 5
Duck Slough (Merced County)

LOE ID:

191737

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 15 samples exceeded the water quality threshold for Nickel.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for nickel incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.1 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164853, Nickel	Region 5
Duck Slough (Merced County)

LOE ID:

191732

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 164853, Nickel	Region 5
Duck Slough (Merced County)

LOE ID:

191717

Pollutant:

Nickel

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 11 samples exceeded the water quality threshold for Nickel.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for nickel incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.1 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2011-11-08

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159510	Region 5
Duck Slough (Merced County)

Pollutant:	Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. One of the 80 samples exceed the objective for Municipal & Domestic Supply. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the 80 samples exceed the objective for Municipal & Domestic Supply and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159510, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 5
Duck Slough (Merced County)

LOE ID:

63163

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 1 of 20 samples exceed the criterion for Nitrate/Nitrite as N.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for nitrate + nitrite (as N) is 10.0 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 12/16/2008-7/20/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159510, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 5
Duck Slough (Merced County)

LOE ID:

331935

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 10 samples exceeded the water quality threshold for Nitrate + Nitrite as N.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Primary California Maximum Contaminant Level for nitrate + nitrite (as N) incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 10 mg/L (California Code of Regulations, Title 22).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-10-09 and 2019-09-10

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159510, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 5
Duck Slough (Merced County)

LOE ID:

192300

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 50 samples exceeded the water quality threshold for Nitrate + Nitrite as N.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nitrate + nitrite (as N) incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 10 mg/L (California Code of Regulations, Title 22).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2018-09-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159517	Region 5
Duck Slough (Merced County)

Pollutant:	Oryzalin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159517, Oryzalin	Region 5
Duck Slough (Merced County)

LOE ID:

63170

Pollutant:

Oryzalin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Oryzalin.

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

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:

Based on USEPA IRIS reference dose (RfD) as a drinking water level, the drinking water health advisory level for Oryzalin is 35 µg/L.

Guideline Reference:

IRIS Database Calculations (summary)

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159517, Oryzalin	Region 5
Duck Slough (Merced County)

LOE ID:

192464

Pollutant:

Oryzalin

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Oryzalin is the USEPA Aquatic Life Benchmark of 13 ug/L for a vascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2017-11-07 and 2017-11-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159517, Oryzalin	Region 5
Duck Slough (Merced County)

LOE ID:

331987

Pollutant:

Oryzalin

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for oryzalin is the USEPA Aquatic Life Benchmark of 13 ug/L for a vascular plant (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-11-07 and 2018-11-07

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	118592	Region 5
Duck Slough (Merced County)

Pollutant:	Oxamyl (Vydate)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Two lines of evidence are available to assess for Municipal and Domestic Supply. One line of evidence is available to assess for Warm Freshwater Habitat. Zero of the 62 samples, reported as a total concentration or with the fraction not reported, exceed the objective for Municipal and Domestic Supply. Zero of the 30 samples, reported as a total concentration, exceed the guideline for Warm Freshwater Habitat. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 62 samples, reported as a total concentration or with the fraction not reported, exceed the objective for Municipal and Domestic Supply. Zero of the 30 samples, reported as a total concentration, exceed the guideline for Warm Freshwater Habitat. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118592, Oxamyl (Vydate)	Region 5
Duck Slough (Merced County)

LOE ID:

192579

Pollutant:

Oxamyl (Vydate)

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for oxamyl is the USEPA Aquatic Life Benchmark of 27 ug/L for chronic toxicity in invertebrates (7 day average).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118592, Oxamyl (Vydate)	Region 5
Duck Slough (Merced County)

LOE ID:

79593

Pollutant:

Oxamyl (Vydate)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

State Water Board staff assessed ILRP data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Oxamyl.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Oxamyl incorporated by reference in the Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins is 50 ug/L (Water Quality Control Plan, Central Valley Region, Sacramento and San Joaquin Basins).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [ Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118592, Oxamyl (Vydate)	Region 5
Duck Slough (Merced County)

LOE ID:

192493

Pollutant:

Oxamyl (Vydate)

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Oxamyl incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.05 mg/L

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159521	Region 5
Duck Slough (Merced County)

Pollutant:	Oxyfluorfen
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159521, Oxyfluorfen	Region 5
Duck Slough (Merced County)

LOE ID:

332012

Pollutant:

Oxyfluorfen

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).

Guideline Reference:

Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-11-07 and 2018-11-07

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159521, Oxyfluorfen	Region 5
Duck Slough (Merced County)

LOE ID:

353139

Pollutant:

Oxyfluorfen

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of oxyfluorfen does not exceed 0.14 ug/L (Bower, et al. 2017).

Guideline Reference:

Water quality criteria report for Oxyfluorfen. Phase III: application of the pesticide water quality criteria methodology.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2017-11-07 and 2018-06-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition


DECISION ID	159511	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:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Eight lines of evidence are available in the administrative record to assess this pollutant. Four of 237 samples exceed the criteria for Aquatic Life and seventeen of 106 samples exceed the criteria for Fish Spawning. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four of 237 samples exceed the criteria for Aquatic Life and seventeen of 106 samples exceed the criteria for Fish Spawning. These do 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:

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

209027

Pollutant:

Oxygen, Dissolved

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

332063

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 1 of 39 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2017-01-10 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

208513

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 11 of 58 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as SPWN is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2016-10-18

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

63171

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:

Water Board staff assessed Ag Waiver data to determine beneficial use support: Six of 82 sample results exceed the criterion for Oxygen, Dissolved.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin River Basin)

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence was collected at five monitoring sites [Duck Slough @ Gurr Rd-535XDSAGR, Duck Slough @ Hwy 59-535XDSHFN, Duck Slough @ Whealan Rd-535XDSAWH, Duck Slough at El Nido Dam-545MRDEDM and Duck Slough @ Hwy 99-535XDSAHN].

Temporal Representation:

Data was collected intermittently to monthly between 2/12/2007 and 7/20/2010. Three pairs of samples were collected within 7-day periods; the sample results for each pair were averaged. One triplet of samples was collected within 7-day period; the sample results were averaged.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159511, 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):

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

209028

Pollutant:

Oxygen, Dissolved

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 2 of 58 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as WARM is 5.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2016-10-18

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

209026

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as SPWN is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159511, Oxygen, Dissolved	Region 5
Duck Slough (Merced County)

LOE ID:

332062

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 6 of 39 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as SPWN is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2017-01-10 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	159527	Region 5
Duck Slough (Merced County)

Pollutant:	Paraquat
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Line of evidence #63172 was replaced by #222088 and #222356. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159527, Paraquat	Region 5
Duck Slough (Merced County)

LOE ID:

192629

Pollutant:

Paraquat

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Paraquat. Although a total of 11 samples were collected, 11 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Paraquat is the USEPA Aquatic Life Benchmark of 0.396 ug/L for a nonvascular plant (acute) for Paraquat dichloride.

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2011-01-18 to 2018-07-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159527, Paraquat	Region 5
Duck Slough (Merced County)

LOE ID:

222088

Pollutant:

Paraquat

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Paraquat. Although a total of 21 samples were collected, 21 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Paraquat is the USEPA Aquatic Life Benchmark of 0.396 ug/L for a nonvascular plant (acute) for Paraquat dichloride.

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN).

Temporal Representation:

Date for this waterbody was collected over the date range 2006-05-17 to 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159527, Paraquat	Region 5
Duck Slough (Merced County)

LOE ID:

222356

Pollutant:

Paraquat

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Paraquat. Although a total of 21 samples were collected, 21 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Paraquat is the USEPA Aquatic Life Benchmark of 0.396 ug/L for a nonvascular plant (acute) for Paraquat dichloride.

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2006-05-17 to 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 159527, Paraquat	Region 5
Duck Slough (Merced County)

LOE ID:

332272

Pollutant:

Paraquat

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Paraquat. Although a total of 1 samples were collected, 1 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for paraquat is the USEPA Aquatic Life Benchmark of 0.396 ug/L for a nonvascular plant (acute) for Paraquat dichloride.

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-08-13 and 2019-08-13

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	159522	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159522, Pendimethalin	Region 5
Duck Slough (Merced County)

LOE ID:

332319

Pollutant:

Pendimethalin

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-02-06 and 2019-02-06

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	159528	Region 5
Duck Slough (Merced County)

Pollutant:	Permethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 159528, Permethrin	Region 5
Duck Slough (Merced County)

LOE ID:

353159

Pollutant:

Permethrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 8 samples were collected, 8 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for permethrin is 1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Permethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2007-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 159528, Permethrin	Region 5
Duck Slough (Merced County)

LOE ID:

332357

Pollutant:

Permethrin

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:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 15 samples were collected, 15 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2018-10-09 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program

Line of Evidence (LOE) for Decision ID 159528, Permethrin	Region 5
Duck Slough (Merced County)

LOE ID:

196897

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

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:

The evaluation guideline for permethrin, 0.89 ug/g, is one-tenth of the median lethal concentration (LC50; 8.9 ug/g) and is normalized by the percentage of organic carbon in the sediment sample. The LC50 8.9 ug/g is the geometric mean of LC50 values for permethrin from Amweg et al. (2005).

Guideline Reference:

Use and Toxicity of Pyrethroid Pesticides in the Central Valley, California, USA. Environmental Toxicology and Chemistry, 24:966-972, with erratum 24:No. 5

Guideline Reference:

Whole-sediment toxicity identification evaluation tools for pyrethroid insecticides: I. piperonyl butoxide addition. Environ. Toxicol. Chem. 26:2389-2396.

Spatial Representation:

Data were collected from 1 station(s). Station Code(s): 535XDSAGR.

Temporal Representation:

Data for this waterbody were collected over the date range 2013-09-10 to 2013-09-10

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159528, Permethrin	Region 5
Duck Slough (Merced County)

LOE ID:

192807

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 3 samples were collected, 3 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The chronic concentration goal for Permethrin is 1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of Permethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR).

Temporal Representation:

Date for this waterbody was collected over the date range 2017-10-10 to 2018-09-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 159528, Permethrin	Region 5
Duck Slough (Merced County)

LOE ID:

353160

Pollutant:

Permethrin

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 17 samples were collected, 17 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Amendment to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins for the Control of Pyrethroid Pesticide Discharges

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2007-02-12 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	118611	Region 5
Duck Slough (Merced County)

Pollutant:	Phorate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. LOE 63177 has been replaced by LOE 222371 and 222373 due to a reassessment of data using a U.S. EPA aquatic life benchmark.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118611, Phorate	Region 5
Duck Slough (Merced County)

LOE ID:

192978

Pollutant:

Phorate

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118611, Phorate	Region 5
Duck Slough (Merced County)

LOE ID:

222373

Pollutant:

Phorate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2009-05-19

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 118611, Phorate	Region 5
Duck Slough (Merced County)

LOE ID:

222371

Pollutant:

Phorate

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):


DECISION ID	171203	Region 5
Duck Slough (Merced County)

Pollutant:	Phosmet
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Previously considered water quality data was reevaluated according to new guidelines as part of this assessment. Lines of evidence have been replaced. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171203, Phosmet	Region 5
Duck Slough (Merced County)

LOE ID:

353196

Pollutant:

Phosmet

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for phosmet is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171203, Phosmet	Region 5
Duck Slough (Merced County)

LOE ID:

353186

Pollutant:

Phosmet

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for phosmet is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2009-05-19

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171203, Phosmet	Region 5
Duck Slough (Merced County)

LOE ID:

353174

Pollutant:

Phosmet

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for phosmet is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertebrate (chronic).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	159529	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 159529, Pyraclostrobin	Region 5
Duck Slough (Merced County)

LOE ID:

332543

Pollutant:

Pyraclostrobin

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:

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for pyraclostrobin is the USEPA Aquatic Life Benchmark of 1.5 ug/L for a nonvascular plant (acute).

Guideline Reference:

QAPP Reference for Irrigated Lands Regulatory Program

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2019-03-08 and 2019-03-08

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):


DECISION ID	118594	Region 5
Duck Slough (Merced County)

Pollutant:	Selenium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Two lines of evidence are available to assess for Municipal and Domestic Supply. Two lines of evidence are available to assess for Warm Freshwater Habitat. Zero of the 44 samples, reported as a total concentration or with the fraction not reported, exceed the objective for Municipal and Domestic Supply. Zero of the 44 samples, reported as a total concentration or with the fraction not reported, exceed the criterion for Warm Freshwater Habitat. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 44 samples, reported as a total concentration or with the fraction not reported, exceed the objective for Municipal and Domestic Supply. Zero of the 44 samples, reported as a total concentration or with the fraction not reported, exceed the criterion for Warm Freshwater Habitat. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 118594, Selenium	Region 5
Duck Slough (Merced County)

LOE ID:

193500

Pollutant:

Selenium

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 5 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118594, Selenium	Region 5
Duck Slough (Merced County)

LOE ID:

193334

Pollutant:

Selenium

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for selenium incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.05 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2014-08-12

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 118594, Selenium	Region 5
Duck Slough (Merced County)

LOE ID:

63181

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Warm Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 30 samples exceed the criterion for Selenium.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The selenium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.005 mg/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Code of Federal Regulations 40 part 131.38 Establishment of numeric criteria for priority toxic pollutants for the State of California. 7/1/2011 Edition

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 118594, Selenium	Region 5
Duck Slough (Merced County)

LOE ID:

63180

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 30 samples exceed the criterion for Selenium.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for selenium is 0.05 mg/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Gurr Rd - 535XDSAGR]

Temporal Representation:

Data was collected over the time period 2/12/2007-5/19/2009.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.


DECISION ID	171197	Region 5
Duck Slough (Merced County)

Pollutant:	Simazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for toxicants (Table 3.1 of the Listing Policy). LOE 63186 has been replaced by LOE 222595 and LOE 222607 due to a reassessment of data using a U.S. EPA aquatic life benchmark. The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

193679

Pollutant:

Simazine

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for Simazine incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.004 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

222607

Pollutant:

Simazine

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

222595

Pollutant:

Simazine

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

63188

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 32 samples exceed the criterion for Simazine.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Simazine is 4 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 2 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN]

Temporal Representation:

Data was collected over the time period 2/12/2007-9/30/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

63187

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 6 samples exceed the criterion for Simazine.

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California primary maximum contaminant level for Simazine is 4 ug/L.

Objective/Criterion Reference:

Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171197, Simazine	Region 5
Duck Slough (Merced County)

LOE ID:

193775

Pollutant:

Simazine

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:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2011-01-18 and 2015-08-11

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):


DECISION ID	165400	Region 5
Duck Slough (Merced County)

Pollutant:	Specific Conductivity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Insufficient information is available to determine beneficial use support for this waterbody-pollutant combination with the statistical power and confidence required by the Listing Policy. Beneficial use support will be reassessed in a future cycle, if more data are available. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 165400, Specific Conductivity	Region 5
Duck Slough (Merced County)

LOE ID:

346569

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 7 samples fall within the range, and 7 of 7 samples fall below the threshold.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference into the Water Quality Control Plan for the Sacramento and San Joaquin River Basins specifies a range for specific conductance of 900-1600 uS/cm assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2010-11-17 and 2016-10-18

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 165400, Specific Conductivity	Region 5
Duck Slough (Merced County)

LOE ID:

346537

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 3 samples fall within the range, and 3 of 3 samples fall below the threshold.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAHN (Duck Slough @ Hwy 99).

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Line of Evidence (LOE) for Decision ID 165400, Specific Conductivity	Region 5
Duck Slough (Merced County)

LOE ID:

332719

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 5 samples fall within the range, and 5 of 5 samples fall below the threshold.

Data Reference:

Field, Habitat, Toxicity, WQ from the Irrigated Lands Regulatory Program for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 535XDSAGR (Duck Slough @ Gurr Rd).

Temporal Representation:

The samples were collected between the dates of 2017-11-07 and 2021-09-22

Environmental Conditions:

QAPP Information:

QAPP Reference for Irrigated Lands Regulatory Program

QAPP Information Reference(s):

QAPP Reference for Irrigated Lands Regulatory Program


DECISION ID	122967	Region 5
Duck Slough (Merced County)

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. NUMBER lines of evidence are available in the administrative record to assess this pollutant. Pursuant to section 6.1.5.9 of the Listing Policy, this assessment utilized the upper limit of the optimal temperature range for rainbow trout for growth and completion of most life stages to interpret the narrative water quality objective for temperature. 49 of 89 samples exceeded the evaluation guideline for COLD. 26 of 63 samples exceeded the evaluation guideline for Fish Migration and Fish Spawning. However, the available data are insufficient to satisfy the Listing Policy requirements for spatial and temporal representation (sections 6.1.5.2 and 6.1.5.3). The surface water grab samples collected did not provide sufficient temporal and spatial representation to determine if temperature conditions experienced by aquatic life were within the optimal temperature range throughout the entire water column or the length of time temperature conditions may have exceeded the optimal temperature range. Available information for this waterbody-pollutant combination is insufficient to determine whether the aquatic beneficial use is supported. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available for this Integrated Report cycle indicating that standards are not met. However, the exceedances of the evaluation guideline indicate that beneficial uses may be threatened. This decision will be reevaluated in the next Integrated Report cycle as more data and information become available. Additional data and information may include information demonstrating that sample location(s) are representative of conditions throughout the waterbody, data from additional sampling locations, continuous monitoring data collected in the waterbody, waterbody-specific information on sensitive resident species, their life stage time frames, and the appropriate temperature thresholds necessary to support each life stage.

Regional Board Decision Recommendation:	This decision was made by SWRCB staff.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

230161

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 2 of 9 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses (Sacramento-San Joaquin River Basin Plans.

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

230343

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed East San Joaquin Water Quality Coalition data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 24 of 54 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2016-10-18

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

230137

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2016-10-18

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

230198

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, Sediment, Toxicity, Water data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAHN)

Temporal Representation:

The samples were collected between the dates of 2010-09-14 and 2012-02-07

Environmental Conditions:

QAPP Information:

Michael L. Johnson LLC. 2015. Quality Assurance Project Plan for Monitoring by the East San Joaquin Water Quality Coalition.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

63189

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 45 of 82 samples exceed the criterion for Water Temperature.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

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:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California (1976)

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 4 monitoring sites [Duck Slough @ Gurr Rd - 535XDSAGR, Duck Slough @ Hwy 99 - 535XDSAHN, Duck Slough @ Whealan Rd - 535XDSAWH, Duck Slough @ Hwy 59 - 535XDSHFN]

Temporal Representation:

Data was collected over the time period 2/12/2007-7/20/2010.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Line of Evidence (LOE) for Decision ID 122967, Temperature, water	Region 5
Duck Slough (Merced County)

LOE ID:

63198

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Ag Waiver data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 4 of 7 samples exceed the criterion for Water Temperature.

Data Reference:

Data for Various Pollutants in Merced Irrigation District, 2005-2008.

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:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California (1976)

Spatial Representation:

Data for this line of evidence for Duck Slough (Merced County) was collected at 1 monitoring site [Duck Slough at El Nido Dam - 545MRDEDM]

Temporal Representation:

Data was collected over the time period 8/1/2007-9/16/2008.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

Data for this line of evidence was collected as part of the Irrigated Lands Regulatory Program.

QAPP Information Reference(s):


DECISION ID	128756	Region 5
Duck Slough (Merced County)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the forty-five samples exceed the evaluation guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the forty-five samples exceed the evaluation guideline and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 128756, Thiobencarb	Region 5
Duck Slough (Merced County)

LOE ID:

222582

Pollutant:

Thiobencarb

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:

Water Board staff assessed ILRP_ESJWQC data for Duck Slough (Merced County) to determine beneficial use support and results are as follows: 1 of 23 samples exceeded the water quality threshold for Thiobencarb.

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Thiobencarb is the USEPA Aquatic Life Benchmark of 1 ug/L for a invertebrate (acute).

Guideline Reference:

Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0.

Spatial Representation:

The samples were collected at 1 monitoring site (535XDSAGR)

Temporal Representation:

The samples were collected between the dates of 2006-05-17 and 2008-09-30

Environmental Conditions:

QAPP Information:

The Quality Assurance Project Plan by the East San Joaquin Water Quality Coalition, Revision 1.0 was followed.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 128756, Thiobencarb	Region 5
Duck Slough (Merced County)

LOE ID:

222541

Pollutant:

Thiobencarb

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:

Data Reference:

Data for Various Pollutants in East San Joaquin, 2004-2009.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for Thiobencarb is the USEPA Aquatic Life Benchmark of 1 ug/L for a invertebrate (acute).

Guideline Reference: