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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 169512, Indicator Bacteria	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

336863

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and the results are as follows: 0 of the 12 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective to protect the REC-1 beneficial use in waters other than Lake Thaoe, where the salinity is less than 1 parts per thousand 95 percent or more of the time applies a statistical threshold value to E. coli of 320 cfu/100 mL, not to be exceeded by more than 10 percent of samples within a calendar month (ISWEBE 2018).

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the days of 2016-05-19 and 2021-11-22 .

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Regional Water Board 6 Bacteria Monitoring.

Line of Evidence (LOE) for Decision ID 169512, Indicator Bacteria	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100151

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed RWB6_BACT_Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and the results are as follows: 0 of the 74 samples exceeded the geomean water quality standard for E. coli. This is a six week rolling geomean that is calculated weekly.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a six-week rolling GEOMETRIC MEAN (GM) of Escherichia coli (E. coli) not to exceed 100 colony forming units per 100 milliliters (cfu/100 mL) (calculated weekly).

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 633WFCB03

Temporal Representation:

The samples were collected between the days of 2010-08-31 and 2015-08-18 .

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 169512, Indicator Bacteria	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100051

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and the results are as follows: 0 of the 7 samples exceeded the Statistical Threshold Value (STV) water quality standard for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Inland Surface Waters, Enclosed Bays, and Estuaries Plan. Part 1: Trash Provisions; Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions; Part 3: Bacteria Provisions and Variance Policy

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 633WFCB03

Temporal Representation:

The samples were collected between the days of 2014-12-08 and 2015-11-19 .

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	76498	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Sodium
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Delist from 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Reason for Delisting:	Other
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Five lines of evidence, three which evaluate data for the AG beneficial use, and one each which evaluate data for the COLD and MUN beneficial uses are available in the administrative record to assess this pollutant. 0 of 43 samples exceeded the water quality objective for the AG beneficial use assessment; 0 of 5 samples evaluated for the MUN beneficial use exceed the water quality objective; Data evaluated for the COLD beneficial use did not pass the quantitation checks required by the 2018 Integrated Report and the computed sample size for this assessment is zero: 0 of 0 samples exceed the objective for the COLD beneficial use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 43 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 76498, Sodium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

97150

Pollutant:

Sodium

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality standard for Sodium.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Per the Drinking Water Standards and Health Advisories (USEPA 2012), the health advisory for sodium for individuals on a sodium-restricted diet is 20 mg/l.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 76498, Sodium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

4601

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Self-monitoring monthly reports from 2000 to 2003. Including Carson River and Indian Creek

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 76498, Sodium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

5688

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural 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:

Table 3 of the Region 6 staff report for the Basin Plan amendments summarizes annual average SAR values for the West Fork Carson River. Lahontan RWQCB staff calculated these averages using historical data on SAR or the component ions. For data collected by the South Tahoe Public Utility District between 1984 and 2002, annual average SAR values ranged from 0.3 to 0.4. The mean annual average value was 0.3. The water quality objective (SAR =1) was attained.

Data Reference:

Self-monitoring monthly reports from 1997 to 2000. Including Carson River and Indian Creek

Memorandum: Summary of water quality analysis for potential CWA 303(d) listing of the lower West Fork of the Carson River. South Lake Tahoe, CA: Lahontan RWQCB

2006. Technical Staff Report for Revised Sodium-Related Standards for the Carson and Walker River Watersheds

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective for Sodium Adsorption Ratio (SAR) in the West Fork Carson River is a limit of 1, as an annual average. (As a ratio, SAR has no units.) The objective includes the formula for calculating SAR and natural sources exclusion language.

The approved plan amendments have not yet been physically incorporated into the text of the Basin Plan. A copy of the amendments is included in the administrative record of the 2008 Integrated Report and is used as a reference in this LOE.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station in this segment was sampled.

Temporal Representation:

The data cited above were collected at approximately monthly intervals between 1984 and 2002, for 211 samples in all. Nineteen annual average calculations were done.

Environmental Conditions:

The West Fork Carson River is an interstate river with headwaters near the Sierra Nevada crest and its lowest point in California in the Carson Valley. It joins the East Fork to form the Carson River in Nevada. Water from the West Fork is used for irrigation of pasture and some field crops in the Carson Valley in California, and it contributes to the irrigation supply in Nevada.

QAPP Information:

The quality assurance requirements of the SWAMP QAPP were met.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 76498, Sodium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

98539

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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 sodium threshold of 69 mg/L, agricultural uses of water should not be limited.

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(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 76498, Sodium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100477

Pollutant:

Sodium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural 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:

Table 3 of the Region 6 staff report for the Basin Plan amendments summarizes annual average SAR values for the West Fork Carson River. Lahontan RWQCB staff calculated these averages using historical data on SAR or the component ions. For data collected by the South Tahoe Public Utility District between 1984 and 2002, annual average SAR values ranged from 0.2 to 0.3. The mean annual average value was 0.3. The water quality objective (SAR =1) was attained.

Data Reference:

Self-monitoring monthly reports from 2000 to 2003. Including Carson River and Indian Creek

Self-monitoring monthly reports from 1997 to 2000. Including Carson River and Indian Creek

Memorandum: Summary of water quality analysis for potential CWA 303(d) listing of the lower West Fork of the Carson River. South Lake Tahoe, CA: Lahontan RWQCB

2007. SWAMP Data for the East Fork and West Fork Carson River Hydrologic Units

2006. Technical Staff Report for Revised Sodium-Related Standards for the Carson and Walker River Watersheds

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Objective/Criterion Reference:

2006. Amendments to the Water Quality Control Plan for the Lahontan Region: Revised Sodium-Related Standards for the Carson and Walker River Watersheds. Adopted October 12, 2006 under Resolution R6T-2006-0047

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The data were collected in a canal diverting water from the West Fork Carson River upstream of the USGS gage at Woodfords.

Temporal Representation:

The data cited above were collected at approximately monthly intervals between 1984 and 2002, for 224 samples in all. Nineteen annual average calculations were done.

Environmental Conditions:

QAPP Information:

The quality assurance requirements of the SWAMP QAPP were met.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	100963	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	2, 6- diethylaniline
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. 0 of the 4 samples exceed the water quality guideline for either the COLD beneficial use and 0 of 4 samples exceed the guideline for the MUN 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. 0 of 4 samples exceeded the guideline in each assessment 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 are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 100963, 2, 6- diethylaniline	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100589

Pollutant:

2, 6- diethylaniline

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 California Department of Pesticide Regulation's online database includes data for the West Fork Carson River at Woodfords. These data were collected in May, June, July and August 1994 as part of the U.S. Geological Survey's
National Water Quality Assessment (NAWQA) program.. Only one of the 46 listed pesticides (pebulate) was detected, in one of four samples. The concentration was reported as 0.0090 ug/L.

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Documentation of water quality criteria for individual pollutants in Lines of Evidence for multipollutant datasets is not required, except for pollutants that exceed a standard or criterion. There are no state or federal water quality standards or criteria for pebulate, the only detectable pollutant in this dataset. The Lahontan Basin Plan includes a narrative water quality objective for pesticides in surface waters that provides that: "Pesticide concentrations, individually or collectively, shall not exceed the lowest detectable leves, using the most recent detection procedures available." For waters designated for the Municipal and Domestic Supply beneficial use, the water quality objective references the California Maximum Contaminant Levels (MCLs) for pesticides.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

The West Fork Carson River is an interstate river with headwaters near the Sierra Nevada crest and its lowest point in California in the Carson Valley, transitional between Sierra and Great Basin ecological conditions. In addition to the Cold Freshwater Habitat beneficial use, the West Fork Carson River is designated for the Spawning, Reproduction, and Development Use. The Woodfords station was sampled as part of the USGS National Water Quality Assessment (NAWQA) study of the Carson River watershed in California and Nevada, as part of a larger study of the Truckee and Carson Rivers and Las Vegas Wash.. Woodfords is upstream of the portion of the watershed used for irrigated agriculture.

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 100963, 2, 6- diethylaniline	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100494

Pollutant:

2, 6- diethylaniline

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	100964	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	2-chloro-4-isopropylamino-6-amino-s-triazine
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. 0 of the 4 samples exceed the water quality guideline for either the COLD beneficial use and 0 of 4 samples exceed the guideline for the MUN 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 does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples in either assessment exceeded the guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 100964, 2-chloro-4-isopropylamino-6-amino-s-triazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100495

Pollutant:

2-chloro-4-isopropylamino-6-amino-s-triazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 100964, 2-chloro-4-isopropylamino-6-amino-s-triazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100590

Pollutant:

2-chloro-4-isopropylamino-6-amino-s-triazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171064	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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 171064, Alachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100593

Pollutant:

Alachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171064, Alachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352933

Pollutant:

Alachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 Department of Pesticide Regulation Database data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Alachlor.

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for alachlor is the USEPA Aquatic Life Benchmark of 1.64 ug/L for a nonvascular plant (acute).

Guideline Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

This is a placeholder for previously assessed data that does not have quality assurance information but would require it under newly developed policies. These LOEs were previously assessed and approved at the Regional, State and Federal level in past cycles. The LOEs needed to be moved and/or reassessed but required this reference code for movement within the decision making database.

QAPP Information Reference(s):


DECISION ID	161957	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Alkalinity as CaCO3
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. Five lines of evidence are available in the administrative record to assess this pollutant. 0 of the 31 samples exceed the evaluation guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 31 samples exceeded the evaluation guidleine and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161957, Alkalinity as CaCO3	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338020

Pollutant:

Alkalinity as CaCO3

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Line of Evidence (LOE) for Decision ID 161957, Alkalinity as CaCO3	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

97057

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The National Recommended Water Quality Criteria for Alkalinity as CaCO3 for the protection of freshwater aquatic life is not less than 20000 ug/L. (National Recommended Water Quality Criteria 2016)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 161957, Alkalinity as CaCO3	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

337856

Pollutant:

Alkalinity as CaCO3

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:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161957, Alkalinity as CaCO3	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

337846

Pollutant:

Alkalinity as CaCO3

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The USEPA recommended alkalinity criterion continuous concentration (CCC) for the protection of aquatic life in freshwater is a minimum value of 20,000 ug/L (4-day average).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	161959	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 161959, Aluminum	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338033

Pollutant:

Aluminum

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The aluminum criterion for the protection of aquatic life, is pH, total hardness, and dissolved organic carbon (DOC) dependent. When total hardness or DOC data were not available, default values based on the level III ecoregions developed by U.S EPA were substituted (EPA, 2018). When pH data were not available, the median pH value for the ecoregion, a pH value from a comparable waterbody, or a pH value from a local study in the same waterbody was used as a comparable surrogate.

Guideline Reference:

Final Aquatic Life Ambient Water Quality Criteria for Aluminum. EPA-822-R-18-001. Washington, D.C.: Office of Water, USEPA.

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161959, Aluminum	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338036

Pollutant:

Aluminum

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Aluminum.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for aluminum is 0.2 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	168676	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Ammonia
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 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 line of evidence is available in the administrative record to assess this pollutant. Zero of 99 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 99 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 168676, Ammonia	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338045

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The total ammonia water quality objective to protect aquatic life in freshwater is temperature and pH dependent and is calculated according to the equation for the four-day criterion defined in Chapter 3 of The Water Quality Control Plan for the Lahontan Region.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2018-08-20 and 2018-08-20

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 168676, Ammonia	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338106

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 168676, Ammonia	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338211

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The un-ionized ammonia water quality objective to protect aquatic life in freshwater is temperature and pH dependent and is calculated according to the equation for the four-day criterion defined in Chapter 3 of The Water Quality Control Plan for the Lahontan Region.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2018-08-20 and 2018-08-20

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

Line of Evidence (LOE) for Decision ID 168676, Ammonia	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100518

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Fish Spawning

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical monitoring (conventional pollutants only)

Data Used to Assess Water Quality:

None of 97 samples exceeded the water quality objective for unionized ammonia. Data were reported as as total ammonia as nitrogen and were converted to unionized ammonia before being compared with the objective. Some samples had temperature or pH values outside the range of the criteria and were not counted.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan objective for unionized ammonia is a function of pH, temperature, and the presence of salmonids. The 4-day chronic criteria for unionized ammonia with salmonids present ranged from 0.0011 mg/L to 0.033 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at SW-01 Carson River, W Fork, Crystal Springs Rd.

Temporal Representation:

Samples were collected from January 2002 to June 2010.

Environmental Conditions:

QAPP Information:

Samples were collected by STPUD and analyzed using STPUD Laboratory quality assurance program.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 168676, Ammonia	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338226

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	161945	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 161945, Arsenic	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338334

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for arsenic incorporated by reference in the Basin Plan is 0.010 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161945, Arsenic	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

44013

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

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 SWAMP data for Carson River, West Fork (Woodfords to Paynesville) to determine beneficial use support and results are as follows: 0 of 1 samples exceed the criterion for Arsenic.

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

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, Lahontan Region).

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for arsenic is 33 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161945, Arsenic	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338331

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 150 ug/L. The conversion factor used to convert the total fraction criterion for arsenic to dissolved fraction criterion is 1. Therefore all data was considered to be representative of the dissolved fraction. (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: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers


DECISION ID	171034	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171034, Atrazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100594

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171034, Atrazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352934

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Atrazine is the USEPA Aquatic Life Benchmark of < 1 ug/L for a nonvascular plant (acute). The benchmark was derived from a 'less-than' value (for example, <1,500) and may underestimate toxicity.

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	100968	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Azinphos-methyl (Guthion)
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. 0 of the 4 samples exceed the water quality guideline for the COLD beneficial use assessment, and 0 of 4 sample exceed the guideline for the MUN beneficial use assessment. 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 does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples exceeded the guideline for the COLD beneficial use assessment 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 per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 100968, Azinphos-methyl (Guthion)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100597

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 100968, Azinphos-methyl (Guthion)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100498

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	161946	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Barium
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 161946, Barium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338339

Pollutant:

Barium

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for barium incorporated by reference in the Water Quality Control Plan, Lahontan Region is 1 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR01 (West Fork Carson River downstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161946, Barium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338338

Pollutant:

Barium

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for barium incorporated by reference in the Water Quality Control Plan, Lahontan Region is 1 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers


DECISION ID	171052	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171052, Benefin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100598

Pollutant:

Benefin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171052, Benefin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352935

Pollutant:

Benefin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for benefin is the USEPA Aquatic Life Benchmark of 1.9 ug/L for a fish (chronic).

Guideline Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171803	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Benthic Community Effects
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:	New data was assessed, and the previous LOE 96361 was retired since that data belongs on a different waterbody. Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. Two lines of evidence evaluating benthic-macroinvertebrate bioassessment data ais available in the administrative record to assess this indicator. 0 of 2 benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. However, a minimum of two benthic-macroinvertebrate samples are required to fully assess listing status. Based on the readily available data and information, the weight of evidence indicates that there is insufficient information to justify placing Benthic Community Effects in this waterbody segment 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. 0 of 2 benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. The available information is insufficient to justify placement of this waterbody/pollutant combination on the 303(d) List of impaired waters at this time. 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:

Line of Evidence (LOE) for Decision ID 171803, Benthic Community Effects	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352772

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 633WFCB03 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.83129183301 to 0.83129183301 .

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in, human, plant, animal, or aquatic life. (Lahontan Basin Plan)

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rhen, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use.)

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

Samples were collected from 2018-08-20 to 2018-08-20.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171803, Benthic Community Effects	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352768

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 633PS0259 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.82678652942 to 0.82678652942 .

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

Samples were collected from 2020-07-29 to 2020-07-29.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):


DECISION ID	78310	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Bifenthrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision and the attached LOE should be retired during the next cycle because they no longer are located in this segment due to re-segmentation of the WF Carson. Text from past decision This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 78310, Bifenthrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43950

Pollutant:

Bifenthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for bifenthrin is the median lethal concentration (LC50) of 0.43 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 0.43 ug/g is the geometric mean of LC50 values for bifenthrin from Amweg et al. (2005) and Amweg and Weston (2007).

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:

Water quality criteria report for bifenthrin.

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	163622	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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 3.2 of the Listing Policy. Under section 3.2 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. 7 of the 43 samples exceed the water quality criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 7 of 43 samples exceeded the criteria and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163622, Boron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100449

Pollutant:

Boron

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:

Data were collected over a 31 year period. On 9 of those years, the annual average exceeded 0.02 mg/L.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site-specific objective in Lahontan Basin Plan Table 3-14 is 0.02 mg/L (= 20 ug/L) as a mean of monthly means. The objective applies upstream from Woodfords under the Tributary Rule.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163622, Boron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

342719

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 5 samples exceeded the water quality threshold for Boron

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Boron in this water body is 0.02 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2020-02-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Line of Evidence (LOE) for Decision ID 163622, Boron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

96858

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Headwaters to Woodfords) to determine beneficial use support and results are as follows: 2 of 6 samples exceeded the water quality standard for Boron. The two exceedances were for 2014 and 2015.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective in the Lahontan Basin Plan for boron for the West Form Carson River at Woodfords (table 3-14) is 0.02 mg/L mean of monthly means. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: "additional beneficial uses may apply to waters with in these categories under the tributary rule, which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 2 monitoring site(s) (633WCR002, 633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163622, Boron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

96859

Pollutant:

Boron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Headwaters to Woodfords) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality standard for Total Boron (0.151 mg/L).

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective in the Lahontan Basin Plan for sulfate for the West Fork Carson River (table 3-14) is 0.02 mg/L mean of monthly means. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: "additional beneficial uses may apply to waters with in these categories under the tributary rule, which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	171053	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171053, Butylate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100544

Pollutant:

Butylate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171053, Butylate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352936

Pollutant:

Butylate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for butylate is the USEPA Aquatic Life Benchmark of 105 ug/L for a fish (acute).

Guideline Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	161947	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 161947, Cadmium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338364

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved cadmium criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 2.2 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161947, Cadmium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338361

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for cadmium incorporated by reference in the Basin Plan is 0.005 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161947, Cadmium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

44061

Pollutant:

Cadmium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for cadmium is 4.98 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	101007	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Carbaryl
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, one each evaluating data for the COLD and MUN beneficial uses are available in the administrative record to assess this pollutant. 0 of 4 samples in either assessment exceed the water quality criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. 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. 0 of 4 samples in either assessment exceeded the criteria 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 per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101007, Carbaryl	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100501

Pollutant:

Carbaryl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 101007, Carbaryl	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100545

Pollutant:

Carbaryl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171035	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 171035, Carbofuran	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352937

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Carbofuran is the USEPA Aquatic Life Benchmark of 0.75 ug/L for an invertibrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171035, Carbofuran	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100548

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	79964	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision and the attached LOE should be retired during the next cycle because they are no longer located in this segment due to re-segmentation of the WF Carson. Text from last cycle This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79964, Chlordane	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

33734

Pollutant:

Chlordane

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected exceeded the criteria for chlordane concentration (Sum of trans-Chlordane, cis-Chlordane, cis-Nonachlor, trans-Nonachlor, and Oxychlordane).

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Lahontan Region (2005): All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or that adversely affects the water for beneficial uses.

Objective/Criterion Reference:

Evaluation Guideline:

The Probable Effect Concentration for Chlordane in freshwater sediments is 17.6 ug/kg.

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 633WCRSED (West Fork Carson River at Paynesville).

Temporal Representation:

One sample was collected on 9/22/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79965	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Chlorpyrifos
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	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 that are both based on the same dataset assessed for COLD and MUN are available in the administrative record to assess this pollutant. 0 of 4 water samples exceed the water quality criteria for the COLD and MUN beneficial uses. 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. 0 of 4 water samples exceeded the criteria for the COLD and MUN beneficial uses. These sample sizes are insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 79965, Chlorpyrifos	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100503

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 79965, Chlorpyrifos	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100549

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	161958	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161958, Chromium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338454

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved chromium (III) criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is is hardness dependent as described in Table 1 of paragraph (b)(1). The value calculated when using a default hardness of 100 mg/L is 180 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161958, Chromium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338457

Pollutant:

Chromium

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for total chromium incorporated by reference in the Water Quality Control Plan, Lahontan Region is 0.05 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161958, Chromium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

44100

Pollutant:

Chromium

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for chromium is 111 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	161948	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161948, Copper	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338526

Pollutant:

Copper

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Secondary Maximum Contaminant Level for total Copper incorporated by reference in the Water Quality Control Plan, Lahontan Region is 1.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161948, Copper	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338488

Pollutant:

Copper

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

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: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161948, Copper	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43804

Pollutant:

Copper

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for copper is 149 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	171054	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 171054, Cyanazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100552

Pollutant:

Cyanazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171054, Cyanazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352938

Pollutant:

Cyanazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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:

OPP Pesticide Ecotoxicity Database.

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	78938	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision and the attached LOE should be retired during the next cycle because they are no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 78938, Cyfluthrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43925

Pollutant:

Cyfluthrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for cyfluthrin is the median lethal concentration (LC50) of 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

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	78939	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 78939, Cyhalothrin, Lambda	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43885

Pollutant:

Cyhalothrin, Lambda

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for lambda-cyhalothrin is the median lethal concentration (LC50) of 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

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79402	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79402, Cypermethrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43915

Pollutant:

Cypermethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for cypermethrin is the median lethal concentration (LC50) of 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 for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	101010	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	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, one each evaluating data for the COLD and MUN beneficial uses are available in the administrative record to assess this pollutant. 0 of 4 samples in either assessment exceed the water quality criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. 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. 0 of 4 samples in either assessment exceeded the criteria 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 per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101010, DDE (Dichlorodiphenyldichloroethylene)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100505

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 101010, DDE (Dichlorodiphenyldichloroethylene)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100553

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	101011	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Dacthal
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, one each evaluating the COLD and MUN beneficial uses are available in the administrative record to assess this pollutant. 0 of 4 samples in either assessment exceed the water quality guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples in either beneficial use assessment exceeded the guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101011, Dacthal	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100556

Pollutant:

Dacthal

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	80065	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Deltamethrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 80065, Deltamethrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43945

Pollutant:

Deltamethrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for deltamethrin is the median lethal concentration (LC50) of 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

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79403	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Diazinon
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	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 that both assess the same dataset for MUN and COLD. 0 of 4 water samples exceed the water quality criteria for the COLD beneficial use and 0 of 4 water samples exceed the criteria for the MUN 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. 0 of 4 water samples exceeded the criteria for the COLD and MUN beneficial uses 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. 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 79403, Diazinon	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100557

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 79403, Diazinon	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100507

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	79404	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Dieldrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	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 that assess the same data for COLD and MUN. 0 of the 4 water samples exceed the water quality criteria for the COLD beneficial use and 0 of 4 water samples exceed the criteria for the MUN beneficial. 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. 0 of 4 water samples exceeded the criteria for the MUN and COLD beneficial uses 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 per beneficial use/pollutant combinations are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 79404, Dieldrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100559

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 79404, Dieldrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100508

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171037	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 171037, Disulfoton	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100560

Pollutant:

Disulfoton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171037, Disulfoton	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352939

Pollutant:

Disulfoton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 Department of Pesticide Regulation Database data for Carson River, West Fork (Hope Valley to Woodfords) 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 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:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Disulfoton is the USEPA Aquatic Life Benchmark of 0.01 ug/L for an invertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171038	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171038, Dyfonate (Fonofos or Fonophos)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352943

Pollutant:

Dyfonate (Fonofos or Fonophos)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Fonofos is the maximum acceptable toxicant concentration (MATC) of 0.45 ug/L. The MATC is calculated as the geometric mean of the lowest observed effect concentration (LOEC) of 0.64 ug/L and the no observed effect concentration (NOEC) of 0.31 ug/L, as determined in a 21 day toxicity study with the water flea, Daphnia magna. Threshold values (LOEC and NOEC) are from USEPA Office of Pesticide Programs Ecotoxicity database.

Guideline Reference:

OPP Pesticide Ecotoxicity Database.

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171038, Dyfonate (Fonofos or Fonophos)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100561

Pollutant:

Dyfonate (Fonofos or Fonophos)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171039	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171039, EPTC (Eptam, s-ethyl dipropylthiocarbamate)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100562

Pollutant:

EPTC (Eptam, s-ethyl dipropylthiocarbamate)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171039, EPTC (Eptam, s-ethyl dipropylthiocarbamate)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352940

Pollutant:

EPTC (Eptam, s-ethyl dipropylthiocarbamate)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for EPTC (eptam, s-ethyl dipropylthiocarbamate) is the USEPA Aquatic Life Benchmark of 40 ug/L for a fish (chronic).

Guideline Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	79518	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Electrical 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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence that assesses for the COLD beneficial use consisting of 341 samples also collected over a 31 year period, are available in the administrative record to assess this pollutant. 0 of the samples exceeded the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 341 samples evaluated for the COLD beneficial use exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 79518, Electrical Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100530

Pollutant:

Electrical Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

341

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected over 31 years. Of the 341 samples collected, none measured above 900 uS/cm.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	79762	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Endrin
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79762, Endrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43824

Pollutant:

Endrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's water quality objective for toxicity states: all waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce determental physiological responses in human, plant, animal, or aquatic life.

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for endrin is 207 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79405	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79405, Esfenvalerate/Fenvalerate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

44313

Pollutant:

Esfenvalerate/Fenvalerate

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for esfenvalerate/fenvalerate is the median lethal concentration (LC50) of 1.5 ug/g and is normalized by the percentage of organic carbon in the sediment sample. The LC50 1.5 ug/g is the geometric mean of LC50 values for esfenvalerate/fenvalerate 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

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	171055	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171055, Ethalfluralin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352941

Pollutant:

Ethalfluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Ethalfluralin is the USEPA Aquatic Life Benchmark of 0.4 ug/L for a fish (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171055, Ethalfluralin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100563

Pollutant:

Ethalfluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171056	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	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 171056, Ethoprop	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100564

Pollutant:

Ethoprop

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171056, Ethoprop	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352942

Pollutant:

Ethoprop

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for ethoprop is the USEPA Aquatic Life Benchmark of 0.8 ug/L for an invertebrate (chronic).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	80196	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from past cycle; This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 80196, Fenpropathrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

44353

Pollutant:

Fenpropathrin

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

The evaluation guideline for fenpropathrin is the median lethal concentration (LC50) of 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 for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville - 633WCRSED]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	161949	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Fluoride
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. 0 of 20 samples exceed the MUN water quality objective (MCL). 0 of 15 samples exceed the AGR 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. 0 of 20 samples exceed the MUN water quality objective (MCL). 0 of 15 samples exceed the AGR evaluation guideline. Neither of these 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 161949, Fluoride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338604

Pollutant:

Fluoride

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Waters designated as AGR shall not contain concentrations of chemical constituents in amounts that adversely affect the water for beneficial uses (i.e., agricultural purposes). (Water Quality Control Plan, Lahontan Region)

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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 1 mg/L criteria is the recommended maximum concentration of Fluoride 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: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161949, Fluoride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338590

Pollutant:

Fluoride

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Fluoride incorporated by reference in the Water Quality Control Plan, Lahontan Region is 2 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161949, Fluoride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338617

Pollutant:

Fluoride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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 1 mg/L criteria is the recommended maximum concentration of Fluoride 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: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2019-12-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Line of Evidence (LOE) for Decision ID 161949, Fluoride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

97181

Pollutant:

Fluoride

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Fluoride incorporated by reference in the Water Quality Control Plan, Lahontan Region is 2 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 161949, Fluoride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338614

Pollutant:

Fluoride

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Fluoride incorporated by reference in the Water Quality Control Plan, Lahontan Region is 2 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2019-12-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers


DECISION ID	101020	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	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. 0 of 4 samples exceed the water quality guideline for each of the COLD and MUN beneficial use assessments. 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 does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples in either assessment exceeded the guideline and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101020, Hexachlorobenzene/ HCB	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100567

Pollutant:

Hexachlorobenzene/ HCB

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 101020, Hexachlorobenzene/ HCB	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100535

Pollutant:

Hexachlorobenzene/ HCB

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	161950	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Iron
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 161950, Iron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338656

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The Red Book states that based on field observations principally, a criterion of 1.0 mg/L iron for freshwater aquatic life is believed to be adequately protective.

Guideline Reference:

Quality Criteria for Water. USEPA Office of Water and Hazardous Materials. Washington, D.C

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161950, Iron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338657

Pollutant:

Iron

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Regions Objective for Municipal and Domestic Supply uses of inland surface waters states that waters designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL). This is based upon drinking water standards specified in the following provisions of Title 22 of the California Code of Regulations which are incorporated by reference into the Water Quality Control Plan: Table 64431-A of Section 64431 (Inorganic Chemicals), Table 64431-B of Section 64431 (Fluoride), Table 64444-A of Section 64444 (Organic Chemicals), Table 64449-A of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The maximum contaminant level listed in Table 64449-A for Iron is 0.3 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):


DECISION ID	79406	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Lead
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79406, Lead	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43844

Pollutant:

Lead

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for lead is 128 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79407	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence, one each assessing water data for the COLD and MUN beneficial uses, are available in the administrative record to assess this pollutant. 0 of 4 water samples exceed the water quality objectives for the COLD and MUN beneficial uses. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 water samples exceeded the objectives for the MUN and COLD beneficial uses and these sample sizes are insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples per beneficial use assessed are needed for application of 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 79407, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100568

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 79407, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100536

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171040	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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 171040, Linuron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352944

Pollutant:

Linuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for linuron is the USEPA Aquatic Life Benchmark of 0.09 ug/L for an invertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171040, Linuron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100571

Pollutant:

Linuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171041	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	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 171041, Malathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100572

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171041, Malathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352945

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of Malathion, does not exceed 0.028 ug/L more than once every three years on the average (UC Davis Aquatic Life Criterion).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: l. Organophosphate insecticides. Reviews of Environmental Contamination and Toxicology 216:1-48.

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	161951	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Manganese
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 161951, Manganese	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338681

Pollutant:

Manganese

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	170620	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 170620, Mercury	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338743

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Mercury. 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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Mercury criteria for the protection of human health from consumption of organisms only is 0.051 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170620, Mercury	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338744

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

National Recommended Water Quality Criteria Continuous Concentrations (4-day average concentrations) for freshwater aquatic organisms exposure to total mercury is 0.77 ug/L.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170620, Mercury	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338763

Pollutant:

Mercury

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The mercury criteria for the protection of human health from the consumption of water and organisms is 0.050 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 170620, Mercury	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43854

Pollutant:

Mercury

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for mercury is 1.06 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	79412	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Methyl Parathion
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant that are based on the same data assessed for MUN and COLD. 0 of 4 water samples assessed for the COLD and MUN beneficial uses exceed the water quality guidelines. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 water samples assessed for the COLD and MUN beneficial uses exceeded the guidelines and these sample sizes are insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples per beneficial use assessed are needed for application of 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 79412, Methyl Parathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100459

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 79412, Methyl Parathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100575

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171057	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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 171057, Metolachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352946

Pollutant:

Metolachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for metolachlor is the USEPA Aquatic Life Benchmark of 8 ug/L for nonvascular plants.

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171057, Metolachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100576

Pollutant:

Metolachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171058	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171058, Metribuzin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352947

Pollutant:

Metribuzin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for metribuzin is the USEPA Aquatic Life Benchmark of 8.1 ug/L for a nonvascular plant (acute).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171058, Metribuzin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100579

Pollutant:

Metribuzin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171042	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171042, Molinate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100580

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171042, Molinate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352948

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for molinate is the USEPA Aquatic Life Benchmark of 105 ug/L for a fish (acute).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171059	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171059, Napropamide	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100583

Pollutant:

Napropamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171059, Napropamide	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352949

Pollutant:

Napropamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for Napropamide is the USEPA Aquatic Life Benchmark of 350 ug/L for a vascular plant (acute).

Guideline Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	161952	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161952, Nickel	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338783

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region?s Objective for Municipal and Domestic Supply uses of inland surface waters states that waters designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL). This is based upon drinking water standards specified in the following provisions of Title 22 of the California Code of Regulations which are incorporated by reference into the Water Quality Control Plan: Table 64431-A of Section 64431 (Inorganic Chemicals), Table 64431-B of Section 64431 (Fluoride), Table 64444-A of Section 64444 (Organic Chemicals), Table 64449-A of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The maximum contaminant level listed in Table 64431-A for nickel is 0.1 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161952, Nickel	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

43864

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for nickel is 48.6 mg/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data for this line of evidence for Carson River, West Fork (Woodfords to Paynesville) was collected at 1 monitoring site [ West Fork Carson River at Paynesville]

Temporal Representation:

Data was collected on a single day 9/22/2008.

Environmental Conditions:

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

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan

Line of Evidence (LOE) for Decision ID 161952, Nickel	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338781

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Commercial or recreational collection of fish, shellfish, or organisms

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The nickel criterion for the protection of human health from consumption of organisms only is 4.6 mg/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161952, Nickel	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

338773

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved nickel 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 52 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).


DECISION ID	101027	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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. One line of evidence is available in the administrative record to assess this pollutant. 0 of the 5 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the 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 do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 5 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101027, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

97128

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nitrate + nitrite (as N) that is incorporated by reference in the Water Quality Control Plan, Lahontan Region is 10.0 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program


DECISION ID	79519	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Nitrogen, Nitrite
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence for the COLD beneficial use consisting of 103 samples collected also over an 8 year period (2002-2010), is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the 103 available samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 79519, Nitrogen, Nitrite	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100517

Pollutant:

Nitrite as Nitrite NO2

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

103

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical monitoring (conventional pollutants only)

Data Used to Assess Water Quality:

None of 103 samples exceeded the water quality objective for nitrite.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan, Lahontan Basin, Objective for Municipal and Domestic Supply uses of inland surface waters states the following: waters shall not contain concentrations of inorganic chemicals in excess of the limits specified in California Code of Regulations, Title 22, Table 64431-A of section 64431 (Inorganic Chemicals). The maximum contaminant level listed in Table 64431-A for Nitrite as N is 1.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at SW-01 Carson River, W Fork, Crystal Springs Rd.

Temporal Representation:

Samples were collected from January 2002 to June 2010.

Environmental Conditions:

QAPP Information:

Samples were collected by STPUD and analyzed using STPUD Laboratory quality assurance program.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	161953	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(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. Eleven lines of evidence are available in the administrative record to assess this parameter: Six which assess dissolved oxygen concentration data and 5 which assess dissolved oxygen percent saturation data. Two of 221 samples are below the objective for minimum dissolved oxygen concentration. Zero of 46 samples are below the objective for minimum dissolved oxygen percent saturation. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 221 samples are below the objective for minimum dissolved oxygen concentration. Zero of 46 samples are below the objective for minimum dissolved oxygen percent saturation. This does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351377

Pollutant:

Oxygen, Dissolved

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 SWAMP Perennial Stream Surveys data to determine beneficial use support and results are as follows:
0 of 1 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351316

Pollutant:

Oxygen, Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 22 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-05-19 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351364

Pollutant:

Oxygen, Dissolved

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2016-05-19 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351359

Pollutant:

Oxygen, Dissolved

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2016-05-19 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351257

Pollutant:

Oxygen, Dissolved

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339413

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-05-19 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351233

Pollutant:

Oxygen, Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351197

Pollutant:

Oxygen, Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 21 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-05-19 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100453

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

127

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected over 31 years. Of the 127 daily averaged samples collected, 2 had dissolved oxygen levels below 7.0 mg/L.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The applicable water quality objective from the Lahontan Basin Plan states: "The dissolved oxygen concentration shall not be depressed by more than 10 percent, below 80 percent saturation, or below 7.0 mg/L at any time, whichever is more restrictive." (Note: this is a watershed-specific narrative objective that differs from the regionwide objectives in Basin Plan Table 3-6.)

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

129944

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Alpine Watershed Group Monitoring Program.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

For waters with the beneficial uses of COLD, COLD with SPWN, WARM, and WARM with SPWN, the minimum dissolved oxygen concentration shall not be less than that specified in Table 3-6. (Water Quality Control Plan, Lahontan Region)

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (WF-WDFD)

Temporal Representation:

The samples were collected between the dates of 2010-09-11 and 2017-03-11

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

QAPP Information Reference(s):

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

Line of Evidence (LOE) for Decision ID 161953, Oxygen, Dissolved	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

351239

Pollutant:

Oxygen, Dissolved

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:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):


DECISION ID	79462	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	PCBs (Polychlorinated biphenyls)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from previous cycle This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79462, PCBs (Polychlorinated biphenyls)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

33261

Pollutant:

PCBs (Polychlorinated biphenyls)

LOE Subgroup:

Pollutant-Sediment

Matrix:

Sediment

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero of 1 sample collected for Total PCBs exceeded the evaluation guideline.

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Waters shall not contain substances in concentrations that result in deposition of material that causes nuisance or that adversely affects the water for beneficial uses (Lahontan Region Basin Plan).

Objective/Criterion Reference:

Evaluation Guideline:

In freshwater sediments the probable effect concentration (predictive of sediment toxicity) for total PCB is 676 ug/Kg dry weight (MacDonald et al. 2000).

Guideline Reference:

Development and evaluation of consensus-based sediment quality guidelines for freshwater ecosystems. Environmental Contamination and Toxicology. 39: 20-31

Spatial Representation:

Data were collected at the following station 633WCRSED (West Fork Carson River at Paynesville).

Temporal Representation:

The samples were collected on 9/22/2008.

Environmental Conditions:

QAPP Information:

The SWAMP QAPP (2008) was followed.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	101028	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Parathion
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, one evaluating data for the MUN beneficial use and one evaluating data for the COLD beneficial use are available in the administrative record to assess this pollutant. 0 of 4 samples in either assessment exceed the water quality guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples in either beneficial use assessment exceeded the guidelines 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 per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101028, Parathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100584

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 101028, Parathion	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100480

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171060	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171060, Pendimethalin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100587

Pollutant:

Pendimethalin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171060, Pendimethalin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352950

Pollutant:

Pendimethalin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171066	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171066, Permethrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100588

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171066, Permethrin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352951

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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 Department of Pesticide Regulation Database data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support, and the results are as follows: 0 of the 0 samples exceeded the evaluation guideline for Permethrin. Although a total of 4 samples were collected, 4 of these samples were not included in the assessment because the laboratory data reporting limit(s) was above the water quality threshold and therefore the results could not be quantified with the level of certainty required by the Listing Policy Section 6.1.5.5.

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The chronic criterion for permethrin is 1 ng/L (expressed as a 4-day average). If the freely dissolved concentrations of permethrin were reported or could be calculated then these values were used for this assessment. In the absence of freely dissolved concentrations, total concentrations were used.

Guideline Reference:

Water Quality Criteria Report for Permethrin

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171061	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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:	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 171061, Phorate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100591

Pollutant:

Phorate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171061, Phorate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352952

Pollutant:

Phorate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for an invertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171043	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171043, Prometon (Prometone)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352953

Pollutant:

Prometon (Prometone)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for prometon (prometone) is the USEPA Aquatic Life Benchmark of 98 ug/L for a nonvascular plant (acute).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171043, Prometon (Prometone)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100592

Pollutant:

Prometon (Prometone)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	101032	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Pronamide
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, one which evaluates data for the COLD beneficial use and one which evaluates data for the MUN beneficial use are available in the administrative record to assess this pollutant. 0 of 4 samples in either assessment exceed the water quality guidelines. 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 do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 4 samples in either beneficial use assessment exceeded the guidelines 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 per beneficial use assessed are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that 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 101032, Pronamide	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100566

Pollutant:

Pronamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 101032, Pronamide	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100595

Pollutant:

Pronamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171062	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171062, Propachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100596

Pollutant:

Propachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171062, Propachlor	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352954

Pollutant:

Propachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for propachlor is the USEPA Aquatic Life Benchmark of 13.5 ug/L for a nonvascular plant (acute).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171044	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Propanil (DCPA mono- and di-acid degrad)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171044, Propanil (DCPA mono- and di-acid degrad)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100599

Pollutant:

Propanil (DCPA mono- and di-acid degrad)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171044, Propanil (DCPA mono- and di-acid degrad)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352955

Pollutant:

Propanil (DCPA mono- and di-acid degrad)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for propanil (DCPA mono- and di-acid degrad) is the USEPA Aquatic Life Benchmark of 2.4 ug/L for a freshwater vertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171051	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171051, Propargite	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100600

Pollutant:

Propargite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171051, Propargite	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352956

Pollutant:

Propargite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for propargite is the USEPA Aquatic Life Benchmark of 7 ug/L for an invertebrate (acute).

Guideline Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	161955	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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 161955, Selenium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340231

Pollutant:

Selenium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

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:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161955, Selenium	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340230

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for selenium incorporated by reference in the Water Quality Control Plan, Lahontan Region is 0.05 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers


DECISION ID	171045	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171045, Simazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100546

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171045, Simazine	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352957

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).

Guideline Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	104514	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. 1 of 3 samples exceed the water quality objective. The one exceeding data point calculated during the previous assessment cycle may have been calculated incorrectly. 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. 1 of 3 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 26 samples are needed to determine if a beneficial use is fully supported using table 3.2. 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 104514, Sodium Adsorption Ratio (SAR)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

133524

Pollutant:

Sodium Adsorption Ratio (SAR)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by the Region 6 SWAMP program in quarterly fashion from 2010 to 2015. SAR ratios were calculated as annual averages and were 0.25 and 0.32. No SAR annual average exceeded the objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The objective for Sodium Absorption Ratio (SAR) in the West Fork of the Carson River (Hope Valley to Woodfords), as stipulated in the Lahontan Basin Plan 3-9, is a ratio not to exceed 1. SAR is calculated as Na/Sqrt((Ca+Mg)/2 in annual average fashion, and the formula uses milliequivalent (mEq) concentrations of each ion. To calculate mEq, the formula is (ion mg/L / molar mass)*valence.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected from one station, 633WFCB03, located at Woodfords Bridge.

Temporal Representation:

Data were collected once in 2014 and in quarterly fashion in 2015.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP.

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 104514, Sodium Adsorption Ratio (SAR)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

133409

Pollutant:

Sodium Adsorption Ratio (SAR)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The annual average for year 2007 was 1.9 and does exceed the water quality objective.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The applicable site specific water quality objective from the amended Lahontan Basin Plan for the West Fork Carson River states that the annual average SAR (sodium adsorption rate) should not exceed 1.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected at the following station: 633WCR002 - West Fork Carson River below Willow Creek.

Temporal Representation:

Data was collected during August 2007 and November 2007.

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	168644	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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)(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. Five lines of evidence are available in the administrative record to assess this pollutant. 0 of 31 samples exceed the objective (MCL). 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. 0 of 31 samples exceed the objective (MCL) and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 168644, Specific Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340470

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:

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) based upon drinking water standards specified in Title 22 of the California Code of Regulations (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's 'Chemical Constituents' objective. The California Secondary MCL for specific conductivity is 900 uS/cm.

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 168644, Specific Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340439

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR01 (West Fork Carson River downstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 168644, Specific Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340389

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Line of Evidence (LOE) for Decision ID 168644, Specific Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

97210

Pollutant:

Specific Conductivity

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's \Chemical Constituents\" objective. The California Secondary MCL for specific conductivity is 900 uS/cm."

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 168644, Specific Conductivity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340668

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:

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers


DECISION ID	171050	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

Regional Board Conclusion:	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 171050, Tebuthiuron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100547

Pollutant:

Tebuthiuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171050, Tebuthiuron	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352958

Pollutant:

Tebuthiuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for tebuthiuron is the USEPA Aquatic Life Benchmark of 50 ug/L for a nonvascular plant (acute).

Guideline Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	78796	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	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. Two lines of evidence are available in the administrative record to assess this pollutant. 0 of the 295 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the 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. 0 of 295 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 78796, Temperature, water	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

33299

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

155

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 155 daily averaged samples exceeded the evaluation guideline for temperature in this water body.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit above or below the natural temperature. For waters designated COLD, the temperature shall not be altered.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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:

Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis

Spatial Representation:

Samples were collected at the following location: SW-05-Carson River, W Fork, Paynesville

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program by Terry Powers, Laboratory Director (March 30, 2009)

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 78796, Temperature, water	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100527

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

140

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 140 daily averaged samples exceeded the evaluation guideline for temperature in this water body.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

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:

Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis

Spatial Representation:

Samples were collected at the following locations in this water body: SW-01: Carson River, W Fork, Crystal Springs Rd D-1: Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program by Terry Powers, Laboratory Director (March 30, 2009)

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171046	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171046, Terbacil	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352959

Pollutant:

Terbacil

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for terbacil is the USEPA Aquatic Life Benchmark of 11 ug/L for a nonvascular plant (acute).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171046, Terbacil	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100550

Pollutant:

Terbacil

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171047	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171047, Terbufos	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100551

Pollutant:

Terbufos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171047, Terbufos	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352960

Pollutant:

Terbufos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for terbufos is the USEPA Aquatic Life Benchmark of 0.03 ug/L for an invertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	171065	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	After review of 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 171065, Thiobencarb	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100554

Pollutant:

Thiobencarb/Bolero

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171065, Thiobencarb	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352961

Pollutant:

Thiobencarb

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for thiobencarb is the USEPA Aquatic Life Benchmark of 1 ug/L for an invertebrate (chronic).

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	79463	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Toxicity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	NOTE: This decision should be retired during the next cycle because it is no longer located in this segment due to re-segmentation of the WF Carson. Text from past cycle: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the sample exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the sample exceeded the guideline and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of 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 region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

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 79463, Toxicity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

32015

Pollutant:

Toxicity

LOE Subgroup:

Toxicity

Matrix:

Sediment

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

TOXICITY TESTING

Data Used to Assess Water Quality:

One sample was collected to evaluate sediment toxicity. The sample did not exhibit significant toxicity. The toxicity test included survival and growth of Hyalella azteca. One sample can have multiple toxicity test results but will be counted only once. One sample is defined as being collected on the same day at the same location with the same lab sample id (if provided).

Data Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Toxicity is defined as a statistically significant effect in the sample exposure compared to the control using EPA-recommended hypothesis testing. For SWAMP data exceedances are counted with the significant effect code SL. SL is defined as the result being significant compared to the negative control based on a statistical test, less than stated the alpha level, AND less than the evaluation threshold.

Guideline Reference:

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

Spatial Representation:

The sample was collected at station 633WCRSED.

Temporal Representation:

The sample was collected in September 2008.

Environmental Conditions:

QAPP Information:

All data was collected following the Standard Operating Procedures and Data Quality Objectives outlined in the SWAMP QAMP, (Puckett, 2002). QA data are included in submission.

QAPP Information Reference(s):

Surface Water Ambient Monitoring Program Quality Assurance Program Plan


DECISION ID	171063	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171063, Triallate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352962

Pollutant:

Triallate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

The evaluation guideline for triallate is the USEPA Aquatic Life Benchmark of 14 ug/L for an invertebrate (chronic).

Guideline Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171063, Triallate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100555

Pollutant:

Triallate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program


DECISION ID	171049	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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 171049, Trifluralin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100558

Pollutant:

Trifluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

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:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, West Fork Carson River at Woodfords, was sampled.

Temporal Representation:

Samples were collected on May 10, June 13, July 12, and August 8, 1994 and analyzed for the 46 listed pesticides.

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 171049, Trifluralin	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

352965

Pollutant:

Trifluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Department of Pesticide Regulation Database Records for the West Fork Carson River and Upper Truckee Rivers

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

UC Davis Aquatic Life Criteria: Aquatic life should not be affected unacceptably if the four-day average concentration of Trifluralin does not exceed 0.33 ug/L in the water column more than once every three years on average (Bower, et al. 2017).

Guideline Reference:

Water Quality Criteria Report for Trifluralin Phase III: Application of the pesticide water quality criteria methodology. Department of Environmental Toxicology University of California, Davis.

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River At Woodfords (NA).

Temporal Representation:

The samples were collected between the dates of 1994-05-10 and 1994-08-08

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):


DECISION ID	161956	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 161956, Zinc	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

341004

Pollutant:

Zinc

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:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region Objective for Municipal and Domestic Supply uses of inland surface waters states that waters designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL). This is based upon drinking water standards specified in the following provisions of Title 22 of the California Code of Regulations which are incorporated by reference into the Water Quality Control Plan: Table 64431-A of Section 64431 (Inorganic Chemicals), Table 64431-B of Section 64431 (Fluoride), Table 64444-A of Section 64444 (Organic Chemicals), Table 64449-A of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The maximum contaminant level listed in Table 64449-A for Zinc is 5 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161956, Zinc	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340998

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The dissolved zinc criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is hardness dependent. The criterion when calculated using a default hardness of 100 mg/L is 120 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161956, Zinc	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340996

Pollutant:

Zinc

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161956, Zinc	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340995

Pollutant:

Zinc

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2021-10-26 and 2021-10-26

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	161954	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340047

Pollutant:

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 SWAMP Perennial Stream Surveys data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339818

Pollutant:

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR01 (West Fork Carson River downstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

340171

Pollutant:

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 23 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339539

Pollutant:

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339937

Pollutant:

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR01 (West Fork Carson River downstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339703

Pollutant:

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCR02 (West Fork Carson River upstream of impacted tributary confluence).

Temporal Representation:

The samples were collected between the dates of 2018-05-10 and 2018-05-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339805

Pollutant:

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:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633PS0259 (Carson River, WF above Cloudburst Cyn. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

339927

Pollutant:

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:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 633WFCB03 (West Fork Carson River at Woodford's Bridge).

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Alpine Watershed Group Monitoring Program.

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

129764

Pollutant:

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:

0 of 0 samples exceeded the water quality standard for pH. Although pH data does exist for this waterbody, the objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality standards could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide objective for pH states: \In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.\""

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (WF-WDFD)

Temporal Representation:

The samples were collected between the dates of 2010-09-11 and 2017-03-11

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

QAPP Information Reference(s):

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

129589

Pollutant:

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:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

33273

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

379

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

There were 379 samples with daily average pH ranging from 5.1 to 8.83.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The applicable objective states: "Changes in normal ambient pH levels shall not exceed 0.5 unit." This is a watershed-specific objective, different from the Lahontan Basin Plan's regionwide objective .

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following location: SW-05 (Carson River, W Fork, Paynesville).

Temporal Representation:

Samples collected between 1981 and 2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

129590

Pollutant:

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:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 161954, pH	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

129756

Pollutant:

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:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Alpine Watershed Group Monitoring Program.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (WF-WDFD)

Temporal Representation:

The samples were collected between the dates of 2010-09-11 and 2017-03-11

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

QAPP Information Reference(s):

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program


DECISION ID	163623	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Chloride
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess this pollutant. Thirty of the 44 samples exceed the objective Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Thirty of 44 samples exceeded the objective, and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163623, Chloride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

96860

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Not Specified

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective in the Lahontan Basin Plan for chloride for the West Form Carson River at Woodfords (table 3-14) is 1.0 mg/L mean of monthly mean. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: "additional beneficial uses may apply to waters with in these categories under the tributary rule, which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 2 monitoring site(s) (633WCR002, 633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2010-08-31 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163623, Chloride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100448

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected for 30 years between 1980 and 2010 (no data were collected in 1982). For those 30 years, the annual average exceeded 1.0 mg/L on 22 of the years.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site-specific objective in Lahontan Basin Plan Table 3-14 is 1.0 mg/L as a mean of monthly means. The objective applies upstream from Woodfords under the Tributary Rule.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 1980 and 2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163623, Chloride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

342804

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP Perennial Stream Surveys data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 1 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163623, Chloride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

342813

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 1 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163623, Chloride	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

342806

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
5 of 6 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 1 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002


DECISION ID	169514	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Nitrogen
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess pollutant. Four of the 5 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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 5 samples exceeded the objective and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169514, Nitrogen	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100486

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

This segment was placed on the Section 303(d) list in 2002 on the basis of calculations by RWQCB staff using data collected by the South Tahoe Public Utility District between 1981 and 2000. The mean of monthly means for total nitrogen in 2000 was 0.20 mg/L, exceeding the objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective for total nitrogen in this segment is 0.15 mg/L, expressed as an annual mean of monthly means. This is a running average incorporating historical data.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The South Tahoe PUD data were collected in a diversion ditch upstream of the USGS gage at Woodfords.

Temporal Representation:

The South Tahoe PUD samples were collected approximately monthly between 1981 and 2000.

Environmental Conditions:

QAPP Information:

The South Tahoe Public Utility District maintains its own laboratory and has a quality assurance program acceptable to the RWQCB.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 169514, Nitrogen	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343153

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
3 of 4 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.15 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2019-12-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 169514, Nitrogen	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

4599

Pollutant:

Nitrogen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	169511	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Nitrogen, Nitrate
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollution

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess pollutant. Four of the11 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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 11 samples exceeded the objective and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169511, Nitrogen, Nitrate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100487

Pollutant:

Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

This segment was placed on the Section 303(d) list in 2002 on the basis of calculations by RWQCB staff using data collected by the South Tahoe Public Utility District between 1981 and 2000. The mean of monthly means for nitrate in 2000 was 0.04 mg/L, exceeding the objective.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective for nitrate (as N) in this segment is 0.02 mg/L, expressed as an annual mean of monthly means. This is a running average incorporating historical data.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The South Tahoe PUD data were collected in a diversion ditch upstream of the USGS gage at Woodfords.

Temporal Representation:

The South Tahoe PUD samples were collected approximately monthly between 1981 and 2000.

Environmental Conditions:

QAPP Information:

The South Tahoe Public Utility District maintains its own laboratory and has a quality assurance program acceptable to the RWQCB.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 169511, Nitrogen, Nitrate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100516

Pollutant:

Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical monitoring (conventional pollutants only)

Data Used to Assess Water Quality:

Two out of 9 annual means of monthly means exceeded the water quality objective for nitrate as nitrogen expressed as an annual mean of monthly means. A total of 102 samples were collected from the two sites.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site specific objective for West Fork Carson River at Woodfords for nitrate as nitrogen is is 0.02 mg/L as means of monthly means.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at SW-01 Carson River, W Fork, Crystal Springs Rd

Temporal Representation:

Samples were collected monthly from January 2002 to June 2010.

Environmental Conditions:

QAPP Information:

Samples were collected by STPUD and analyzed using STPUD Laboratory quality assurance program.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 169511, Nitrogen, Nitrate	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343041

Pollutant:

Nitrogen, Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Nitrate as N

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrate as N in this water body is 0.02 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2019-07-30 and 2019-12-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002


DECISION ID	163624	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Phosphorus
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess pollutant. Eleven of the 21 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Eleven of 21 samples exceeded the objective, and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163624, Phosphorus	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100478

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

This segment was placed on the Section 303(d) list in 2002 on the basis of calculations by RWQCB staff using data collected by the South Tahoe Public Utility District between 1981 and 2000. The means of monthly means during the assessment period beginning in 1997 were as follows: 1997, 0.09 mg/L; 1998, 0.03 mg/L, 1999, 0.02 mg/L, 2000, 0.03 mg/L.

Data Reference:

2007. SWAMP Data for the East Fork and West Fork Carson River Hydrologic Units

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The water quality objective for total phosphorus in thiis segment is 0.02 mg/L, expressed as an annual mean of monthly means. This is a running average incorporating historical data.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The South Tahoe PUD data were collected in a diversion ditch upstream of the USGS gage at Woodfords.

Temporal Representation:

The South Tahoe PUD samples were collected approximately monthly between 1981 and 2000.

Environmental Conditions:

QAPP Information:

The South Tahoe Public Utility District maintains its own laboratory and has a quality assurance program acceptable to the RWQCB.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163624, Phosphorus	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100526

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical monitoring (conventional pollutants only)

Data Used to Assess Water Quality:

Three out of nine annual means of monthly means exceeded the water quality objective for total phosphorus expressed as an annual mean of monthly means. A total of 102 samples were collected from the site.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site specific objective for West Fork Carson River at Woodfords for total phosphorus is 0.02 mg/L as means of monthly means.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at following sampling sites: SW-01 Carson River, W Fork, Crystal Springs Rd.

Temporal Representation:

Samples were collected monthly from January 2002 to June 2010.

Environmental Conditions:

QAPP Information:

Samples were collected by STPUD and analyzed using STPUD Laboratory quality assurance program.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163624, Phosphorus	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343255

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
3 of 6 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.02 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163624, Phosphorus	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343269

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.02 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163624, Phosphorus	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343254

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP Perennial Stream Surveys data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.02 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6


DECISION ID	163625	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Sulfates
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Seven lines of evidence are available in the administrative record to assess this pollutant. Thirty of the 44 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Thirty of the 44 samples exceed the objective, and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343339

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
3 of 5 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 2 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2020-02-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343357

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 2 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343351

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP Perennial Stream Surveys data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 2 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343355

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 2 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

96862

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Headwaters to Woodfords) to determine beneficial use support and results are as follows: 4 of 6 samples exceeded the water quality standard for Sulfate. Exceedances were in 2010, 2013 , 2014, and 2015.

Data Reference:

SWAMP Data:

Water Quality Objective/Criterion:

The site specific objective in the Lahontan Basin Plan for sulfate for the West Form Carson River at Woodfords (table 3-14) is 2.0 mg/L mean of monthly mean. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: "additional beneficial uses may apply to waters with in these categories under the tributary rule, which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 2 monitoring site(s) (633WCR002, 633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2010-08-31 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100450

Pollutant:

Sulfates

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:

Data were collected over a 28 year period. On 22 of those years, the annual average exceeded 2.0 mg/L. Exceedances for years 1983-1986 were not considered since the detection limit was above the site-specific objective.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site-specific objective for sulfate is 2.0 mg/L as a mean of monthly means (applied upstream through the Tributary Rule from the West Fork Carson River at Woodfords station). See Basin Plan Table 3-14.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 9/12/1983 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163625, Sulfates	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343345

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 2 samples exceeded the water quality threshold for Sulfate

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 2 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).


DECISION ID	163626	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Total Dissolved Solids
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Six lines of evidence are available in the administrative record to assess this pollutant. Thirteen of the 45 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Thirteen of 45 samples exceeded the objective, and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

96864

Pollutant:

Total Dissolved Solids

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Headwaters to Woodfords) to determine beneficial use support and results are as follows: 0 of 25 samples exceeded the water quality standard for Total Dissolved Solids.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective in the Lahontan Basin Plan for TDS for the West Form Carson River at Woodfords (table 3-14) is 55 mg/L mean of monthly means. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: "additional beneficial uses may apply to waters with in these categories under the tributary rule, which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 2 monitoring site(s) (633WCR002, 633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100452

Pollutant:

Total Dissolved Solids

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:

Data were collected over 31 years. For eight of those years, the annual average exceeded 55 mg/L.

Data Reference:

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site-specific objective for total dissolved solids (TDS) is 55 mg/L as a mean of monthly means (applied upstream through the Tributary Rule from the West Fork Carson River at Woodfords station). See Lahontan Basin Plan Table 3-14.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343410

Pollutant:

Total Dissolved Solids

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 3 samples exceeded the water quality threshold for Total Dissolved Solids

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Total Dissolved Solids in this water body is 55 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343417

Pollutant:

Total Dissolved Solids

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Total Dissolved Solids

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Total Dissolved Solids in this water body is 55 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343419

Pollutant:

Total Dissolved Solids

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Total Dissolved Solids

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Total Dissolved Solids in this water body is 55 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163626, Total Dissolved Solids	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343421

Pollutant:

Total Dissolved Solids

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
3 of 3 samples exceeded the water quality threshold for Total Dissolved Solids

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Total Dissolved Solids in this water body is 55 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2018-08-20 and 2020-02-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010


DECISION ID	169513	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Total Kjeldahl Nitrogen (TKN)
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess pollutant. Ten of the 14 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Ten of 14 samples exceeded the objective and this exceeds the allowable frequency listed in Table 4.1 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169513, Total Kjeldahl Nitrogen (TKN)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100515

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical monitoring (conventional pollutants only)

Data Used to Assess Water Quality:

Seven out of 9 annual means of monthly means exceeded the water quality objective for Total Kjeldahl Nitrogen expressed as an annual mean of monthly means. A total of 102 samples were collected from the two sites.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The site specific objective for West Fork Carson River at Woodfords for Total Kjeldahl Nitrogen is 0.13 mg/L as means of monthly means.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at SW-01 Carson River, W Fork, Crystal Springs Rd.

Temporal Representation:

Samples were collected monthly from January 2002 to June 2010.

Environmental Conditions:

QAPP Information:

Samples were collected by STPUD and analyzed using STPUD Laboratory quality assurance program.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 169513, Total Kjeldahl Nitrogen (TKN)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100488

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

This segment was placed on the Section 303(d) list in 2002 on the basis of calculations by RWQCB staff using data collected by the South Tahoe Public Utility District between 1981 and 2000. The mean of monthly means for total Kjeldahl nitrogen in 2000 was 0.20 mg/L, exceeding the objective.

Data Reference:

Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective for total Kjeldahl nitrogen in this segment is 0.13 mg/L, expressed as an annual mean of monthly means. This is a running average incorporating historical data.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The South Tahoe PUD data were collected in a diversion ditch upstream of the USGS gage at Woodfords.

Temporal Representation:

The South Tahoe PUD samples were collected approximately monthly between 1981 and 2000.

Environmental Conditions:

QAPP Information:

The South Tahoe Public Utility District maintains its own laboratory and has a quality assurance program acceptable to the RWQCB.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 169513, Total Kjeldahl Nitrogen (TKN)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343522

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 2 samples exceeded the water quality threshold for Nitrogen, Total Kjeldahl

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total Kjeldahl in this water body is 0.13 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 169513, Total Kjeldahl Nitrogen (TKN)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343528

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Nitrogen, Total Kjeldahl

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total Kjeldahl in this water body is 0.13 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 169513, Total Kjeldahl Nitrogen (TKN)	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343527

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Nitrogen, Total Kjeldahl

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total Kjeldahl in this water body is 0.13 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2017-10-09 and 2021-11-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Data for temperature, nutrients, and bacteria in Heavenly Valley Creek (USFS boundary to Trout Creek) and various water bodies in Alpine County, Jul 1980-Jun. 2010


DECISION ID	163627	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

Pollutant:	Turbidity
Final Listing Decision:	Do Not Delist from 303(d) list (associated with a USEPA accepted Advanced Restoration Plan)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	West Fork Carson River Multiple Pollutants Vision Plan
TMDL Project Code:	644
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal from the CWA section 303(d) List under section 4.2 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Seven lines of evidence are available in the administrative record to assess this pollutant. Twelve of the 51 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the 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. Twelve of 51 samples exceeded the objective and this exceeds the allowable frequency listed in Table 4.2 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

100451

Pollutant:

Turbidity

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:

Data were collected over 31 years. For seven of those years, the annual average exceeded 2 NTU.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's objective for turbidity states: "The turbidity shall not be raised above a mean of monthly means value of 2 NTU. (This objective is approximately equal to the State of Nevada standard of 2 NTU annual mean)." This is a watershed-specific objective that differs from the regionwide narrative objective.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Sample collected at the following locations: SW-01-Carson River, W Fork, Crystal Springs Rd D-1-Carson River, West Fork @ Diversion

Temporal Representation:

Samples collected between 7/8/1980 and 6/2/2010.

Environmental Conditions:

QAPP Information:

South Tahoe Public Utility District Laboratory Quality Assurance Program (by Terry Powers, Laboratory Director). March 30, 2009.

QAPP Information Reference(s):

South Lake Tahoe Public Utility District Laboratory Quality Assurance Program

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

98198

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 Alpine Watershed Group Monitoring Program data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality standard for Turbidity. For purposes of this assessment the mean of monthly means is calculated on an annual basis, giving eight years possible for assessment using this data.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Alpine Watershed Group Monitoring Program.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The watershed-wide objective for turbidity in the West Fork Carson River hydrologic unit, as stipulated in the Lahontan Basin Plan page 3-9, is a mean-of-monthly means not to exceed 2 NTU.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (WF-WDFD)

Temporal Representation:

The samples were collected between the dates of 2010-09-11 and 2017-03-11

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

QAPP Information Reference(s):

Quality Assurance Project Plan for Alpine Watershed Group Volunteer Citizen Water Quality Monitoring Program

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

98228

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data for Carson River, West Fork (Hope Valley to Woodfords) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality standard for Turbidity. For purposes of this assessment the mean of monthly means is calculated on an annual basis, giving two years possible for assessment using this data.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP RWB6 Monitoring (tissue and water).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The watershed-wide objective for turbidity in the West Fork Carson River hydrologic unit, as stipulated in the Lahontan Basin Plan page 3-9, is a mean-of-monthly means not to exceed 2 NTU.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2014-12-08 and 2015-11-19

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Quality Assurance Program Plans, Quality Assurance Project Plans, and Standard Operating Procedures for the SWAMP program

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343470

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Turbidity

Data Reference:

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 2 (NTU), (as a MOMM).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River downstream of impacted tributary confluence (633WFCR01)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343459

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP Perennial Stream Surveys data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Turbidity

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 2 (NTU), (as a MOMM).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Carson River, WF above Cloudburst Cyn. Cr. (633PS0259)

Temporal Representation:

The samples were collected between the dates of 2020-07-29 and 2020-07-29

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343465

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Turbidity

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 2 (NTU), (as a MOMM).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River upstream of impacted tributary confluence (633WFCR02)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, Tissue, Toxicity, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163627, Turbidity	Region 6
Carson River, West Fork (Hope Valley to Woodfords)

LOE ID:

343428

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

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 SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
3 of 7 samples exceeded the water quality threshold for Turbidity

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 2 (NTU), (as a MOMM).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: West Fork Carson River at Woodford's Bridge (633WFCB03)

Temporal Representation:

The samples were collected between the dates of 2016-03-24 and 2022-06-09

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):