Final California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	East Walker River, above Bridgeport Reservoir
Water Body ID:	CAR6303005020011214105850
Water Body Type:	River & Stream


DECISION ID	69501	Region 6
East Walker River, above Bridgeport Reservoir

Pollutant:	Indicator Bacteria
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with action other than TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by action other than TMDL)(2016)
Revision Status	Revised
Sources:	Agricultural Water Diversion \| Agriculture-grazing \| Grazing-Related Sources \| Natural Sources \| Pasture Grazing-Riparian and/or Upland \| Streambank Modification/Destabilization \| Unknown Nonpoint Source
Expected Attainment Date:	2028
Implementation Action Other than TMDL:	This listing is being addressed through the implementation of management practices for livestock grazing under Lahontan RWQCB Resolution R6T-2017-0033, Waiver of Waste Discharge Requirements for Grazing Operations in the East Walker River Watershed (Bridgeport Valley and Tributaries) of the Lahontan Region.
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and 4.2 of the Listing Policy. Under 4.2 of the Policy, a minimum of one line of evidence is needed to assess listing status. Fifteen lines of evidence are available in the administrative record to assess this pollutant. 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. There is sufficient justification to place it in the Being Addressed portion of the CWA section 303(d) List because a the RWQCB has determined that an existing regulatory program is reasonably expected to result in attainment of the standard within a reasonable, specified time frame. In 2017 the Lahontan Water Board approved Resolution R6T-2017-0033, Waiver of Waste Discharge Requirements for Grazing Operations in the East Walker River Watershed (Bridgeport Valley and Tributaries) of the Lahontan Region. This waiver is designed to improve water quality in the Bridgeport Valley, of which mid-branch Buckeye Creek is a waterbody. The waiver expects water quality to attain WQOs by 2028. 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. 23 of 51 E. coli samples assessed against the REC-1 beneficial use and 59 of 92 fecal coliform samples assessed against the MUN beneficial use exceeded the water quality objectives and these exceed the allowable frequency listed in Table 4.2 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 removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

133986

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 Bridgeport Reservoir to determine beneficial use support and the results are as follows: 5 of the 9 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 Regional Water Board 6 Bacteria Monitoring.

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 STATISTICAL THRESHOLD VALUE (STV) of 320 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): EWK.08

Temporal Representation:

The samples were collected between the days of 2014-06-03 and 2015-10-14 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

133987

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

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 Bridgeport Reservoir to determine beneficial use support and the results are as follows: 7 of the 9 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard 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 Regional Water Board 6 Bacteria Monitoring.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. (Lahontan Region Basin Plan)

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), station(s): EWK.08

Temporal Representation:

The samples were collected between the days of 2014-06-03 and 2015-10-14 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

99858

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 4 of the 11 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): 630EWK006

Temporal Representation:

The samples were collected between the days of 2011-06-13 and 2013-08-27 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

99878

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 Eastern Sierra Ambient Monitoring data for East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 1 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 Eastern Sierra Ambient Monitoring.

SWAMP Data:

Non-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): 630EWK006

Temporal Representation:

The samples were collected between the days of 2012-08-14 and 2013-10-16 .

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology

QAPP Information Reference(s):

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology (SNARL - CESAME)

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

99920

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 4 of the 13 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 Regional Water Board 6 Bacteria Monitoring.

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): 630EWK006

Temporal Representation:

The samples were collected between the days of 2014-05-13 and 2015-10-15 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129386

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 17 of the 28 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily.

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2010-10-22 and 2013-08-27 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129480

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 9 of the 13 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard 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 Regional Water Board 6 Bacteria Monitoring.

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2014-05-13 and 2015-10-15 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129241

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 8 of the 16 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard 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:

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2010-10-22 and 2013-08-27 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129315

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 10 of the 13 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily.

Data Reference:

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

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2014-05-13 and 2015-10-15 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129136

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Eastern Sierra Ambient Monitoring data for East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 3 of the 6 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard 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 Eastern Sierra Ambient Monitoring.

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2013-03-25 and 2013-10-16 .

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology

QAPP Information Reference(s):

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology (SNARL - CESAME)

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

129453

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Eastern Sierra Ambient Monitoring data for East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 5 of the 7 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Eastern Sierra Ambient Monitoring.

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), station(s): 630EWK006

Temporal Representation:

The samples were collected between the days of 2013-03-25 and 2013-10-16 .

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology

QAPP Information Reference(s):

Quality Assurance Project Plan Sierra Nevada Aquatic Research Laboratory Center for Eastern Sierra Aquatic Microbial Ecology (SNARL - CESAME)

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

27588

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Water column surveys (e.g. fecal coliform)

Data Used to Assess Water Quality:

The East Walker River segment above Bridgeport Reservoir was placed on the Section 303(d) list in 2002 for pathogens as a result of sampling in 2000 and 2001 by the U.S. Geological Survey. At least 8 of 17 monthly fecal coliform samples from the Highway 395 station, and at least 6 of 14 samples at the Bridgeport Reservoir station exceeded the 40 colonies per 100 mL limit. Fecal coliform counts ranged from "K3" to "K60" colonies per 100 mL. Some of the sampling results were reported with a "K" code indicating that the bacteria count was outside of the acceptable range or ideal count of 20-60 colonies per plate. Samples without K codes ranged from 8 to 270 colonies per 100 mL.These USGS data were part of the longer study referenced as Rockwell and Honeywell.

Data Reference:

Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide Water Quality objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, East Walker River above Bridgeport Reservoir, was sampled.

Temporal Representation:

Samples were collected monthly between April 2000 and June 2001.

Environmental Conditions:

The East Walker River originates in the Hunewill Hills east of the Sierra Nevada crest. It flows through Bridgeport Valley and the town of Bridgeport before entering Bridgeport Reservoir.

QAPP Information:

The study was done using USGS quality assurance procedures.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

4606

Pollutant:

Pathogens

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Water Contact Recreation

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:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

133988

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

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), station(s): EWK.08

Temporal Representation:

The samples were collected between the days of 2014-06-03 and 2015-10-14 .

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 69501, Indicator Bacteria	Region 6
East Walker River, above Bridgeport Reservoir

LOE ID:

99841

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 East Walker River, above Bridgeport Reservoir to determine beneficial use support and the results are as follows: 9 of the 11 samples exceeded the geomean water quality standard for E. coli. This is a six week rolling geomean that is calculated weekly.

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 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): 630EWK006

Temporal Representation:

The samples were collected between the days of 2011-06-13 and 2013-08-27 .

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