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

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name:	Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)
Water Body ID:	CAR5366004020200206033625
Water Body Type:	River & Stream


DECISION ID	160321	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

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 160321, Aluminum	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329670

Pollutant:

Aluminum

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins; Fifth Edition. Revised May 2018 (with approved amendments)

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: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160307	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Arsenic
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 160307, Arsenic	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329699

Pollutant:

Arsenic

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160307, Arsenic	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329701

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dissolved arsenic criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater 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: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160308	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Chloride
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 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329813

Pollutant:

Chloride

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Chloride. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference into the Water Quality Control Plan for the Sacramento and San Joaquin River Basins specifies a range for chloride of 250-500 mg/L assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329770

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329737

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329819

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329795

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329800

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160308, Chloride	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329756

Pollutant:

Chloride

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160309	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Cobalt
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 160309, Cobalt	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329827

Pollutant:

Cobalt

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Water Quality for Agriculture, published by the Food and Agriculture Organization of the United Nations in 1985, contains criteria protective of various agricultural uses of water. These criteria were used to translate narrative water quality objectives for chemical constituents that prohibit chemicals in concentrations that would impair agricultural uses of water. The recommended maximum concentration of cobalt in irrigation water is 0.05 mg/L.

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160310	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Copper
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 160310, Copper	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329832

Pollutant:

Copper

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160312	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Nickel
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. LOEs for this waterbody-pollutant combination from previous cycles were reviewed, determined to be inaccurate, and removed.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 160312, Nickel	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329895

Pollutant:

Nickel

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-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: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160312, Nickel	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329901

Pollutant:

Nickel

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Primary Maximum Contaminant Level for nickel incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 0.1 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	167079	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Nitrogen, Nitrate
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 167079, Nitrogen, Nitrate	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329947

Pollutant:

Nitrogen, Nitrate

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Primary California Primary Maximum Contaminant Level for Nitrate as N incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 10 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 167079, Nitrogen, Nitrate	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329946

Pollutant:

Nitrogen, Nitrate

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Primary California Primary Maximum Contaminant Level for Nitrate as N incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 10 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 167079, Nitrogen, Nitrate	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329965

Pollutant:

Nitrogen, Nitrate

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Primary California Primary Maximum Contaminant Level for Nitrate as N incorporated by reference in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins is 10 mg/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160313	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

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

Regional Board Conclusion:	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 160313, Oxygen, Dissolved	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330042

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 Adventure Scientists (Volunteer)* data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.92.119.44 (Tuolumne Wild and Scenic River-37.92.119.44).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160313, Oxygen, Dissolved	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330000

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.6 (Tuolumne Wild and Scenic River-37.93.119.6).

Temporal Representation:

The samples were collected between the dates of 2021-07-03 and 2021-07-03

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160313, Oxygen, Dissolved	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

332033

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 Reference Condition Management Plan data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the 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 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 536TMRBDC (Tuolumne River ~0.6mi below Delaney Cr.).

Temporal Representation:

The samples were collected between the dates of 2022-08-31 and 2022-08-31

Environmental Conditions:

QAPP Information:

SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 160313, Oxygen, Dissolved	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330032

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160313, Oxygen, Dissolved	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330046

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The minimum dissolved oxygen concentration for waters designated as COLD is 7.0 mg/L. (Water Quality Control Plan, Central Valley Region, Sacramento River Basin and San Joaquin Basin)

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.46 (Tuolumne Wild and Scenic River-37.93.119.46).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	165527	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Specific Conductivity
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 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330276

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference into the Water Quality Control Plan for the Sacramento and San Joaquin River Basins specifies a range for specific conductance of 900-1600 uS/cm assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2013-08-28 and 2013-08-28

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330210

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.6 (Tuolumne Wild and Scenic River-37.93.119.6).

Temporal Representation:

The samples were collected between the dates of 2021-07-03 and 2021-07-03

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330277

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.46 (Tuolumne Wild and Scenic River-37.93.119.46).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330181

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 3 samples fall within the range, and 3 of 3 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-10-08 and 2016-09-01

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

332830

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Reference Condition Management Plan data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 536TMRBDC (Tuolumne River ~0.6mi below Delaney Cr.).

Temporal Representation:

The samples were collected between the dates of 2022-08-31 and 2022-08-31

Environmental Conditions:

QAPP Information:

SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330249

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330204

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330270

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.92.119.44 (Tuolumne Wild and Scenic River-37.92.119.44).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330200

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330235

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 165527, Specific Conductivity	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330266

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for SpecificConductivity. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160315	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Sulfates
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 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330356

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference into the Water Quality Control Plan for the Sacramento and San Joaquin River Basins specifies a range for sulfate of 250-500 mg/L assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330355

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330349

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330376

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330365

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330384

Pollutant:

Sulfates

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330296

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160315, Sulfates	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330291

Pollutant:

Sulfates

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Sulfate. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160316	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Fourteen lines of evidence are available in the administrative record to assess this pollutant. Pursuant to section 6.1.5.9 of the Listing Policy, this assessment utilized the upper limit of the optimal temperature range for rainbow trout for growth and completion of most life stages to interpret the narrative water quality objective for temperature. Zero of 36 samples exceeded the evaluation guideline applied to protect the COLD beneficial use. However, the available data are insufficient to satisfy the Listing Policy requirements for spatial and temporal representation (sections 6.1.5.2 and 6.1.5.3). The surface water grab samples collected did not provide sufficient temporal and spatial representation to determine if temperature conditions experienced by aquatic life were within the optimal temperature range throughout the entire water column or the length of time temperature conditions may have exceeded the optimal temperature range. Available information for this waterbody-pollutant combination is insufficient to determine whether the aquatic beneficial use is supported. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available for this Integrated Report cycle indicating that standards are not met. This decision may be reevaluated in the next Integrated Report cycle as more data and information become available. Additional data and information may include information demonstrating that sample location(s) are representative of conditions throughout the waterbody, data from additional sampling locations, continuous monitoring data collected in the waterbody, waterbody-specific information on sensitive resident species, their life stage time frames, and the appropriate temperature thresholds necessary to support each life stage.

Regional Board Decision Recommendation:	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 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330406

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses (Sacramento-San Joaquin River Basin Plans).

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.6 (Tuolumne Wild and Scenic River-37.93.119.6).

Temporal Representation:

The samples were collected between the dates of 2021-07-03 and 2021-07-03

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330425

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.46 (Tuolumne Wild and Scenic River-37.93.119.46).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330428

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 9 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-04-30 and 2014-08-12

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330433

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330435

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.92.119.44 (Tuolumne Wild and Scenic River-37.92.119.44).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330442

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330454

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330469

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330479

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2013-07-30 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330487

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330504

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

332909

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Reference Condition Management Plan data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for Temperature.

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: 536TMRBDC (Tuolumne River ~0.6mi below Delaney Cr.).

Temporal Representation:

The samples were collected between the dates of 2022-08-31 and 2022-08-31

Environmental Conditions:

QAPP Information:

SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

206482

Pollutant:

Temperature, water

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 NWIS data for Tuolumne River west of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site (USGS-11274790)

Temporal Representation:

The samples were collected between the dates of 2014-10-08 and 2016-09-01

Environmental Conditions:

QAPP Information:

QAPP not requred

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 160316, Temperature, water	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

206324

Pollutant:

Temperature, water

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 STORET data for Tuolumne River west of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 10 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site (CALWR_WQX-B4185010)

Temporal Representation:

The samples were collected between the dates of 2010-10-12 and 2015-10-27

Environmental Conditions:

QAPP Information:

STORET

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.


DECISION ID	160317	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Total Dissolved Solids
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 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330566

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference into the Water Quality Control Plan for the Sacramento and San Joaquin River Basins specifies a range for total dissolved solids of 500-1000 mg/L assessed as an annual average.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330555

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330565

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330523

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330564

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330541

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160317, Total Dissolved Solids	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330539

Pollutant:

Total Dissolved Solids

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 USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the upper limit of the range for Total Dissolved Solids. Additionally, 0 of the 1 samples fall within the range, and 1 of 1 samples fall below the threshold.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160319	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Vanadium
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 160319, Vanadium	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330582

Pollutant:

Vanadium

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Agricultural Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160318	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Zinc
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 160318, Zinc	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330594

Pollutant:

Zinc

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-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: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638


DECISION ID	160314	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

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)(2020)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Fifteen lines of evidence are available in the administrative record to assess this pollutant. Three of the 30 samples exceeded the objective for COLD. Three of the 10 samples exceeded the objective for REC-1 and REC-2. 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. Three of the 30 samples exceeded the objective for COLD. Three of the 10 samples exceeded the objective for REC-1 and REC-2. 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 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

204294

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 STORET data for Tuolumne River west of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 3 of 10 samples exceeded the water quality threshold for pH.

Data Reference:

WQX data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (CALWR_WQX-B4185010)

Temporal Representation:

The samples were collected between the dates of 2010-10-12 and 2015-10-27

Environmental Conditions:

QAPP Information:

STORET

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

204295

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (CALWR_WQX-B4185010)

Temporal Representation:

The samples were collected between the dates of 2010-10-12 and 2015-10-27

Environmental Conditions:

QAPP Information:

STORET

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

204804

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Non-Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX data for the 2020/2022 integrated report in Region 5.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site (CALWR_WQX-B4185010)

Temporal Representation:

The samples were collected between the dates of 2010-10-12 and 2015-10-27

Environmental Conditions:

QAPP Information:

STORET

QAPP Information Reference(s):

This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330071

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.6 (Tuolumne Wild and Scenic River-37.93.119.6).

Temporal Representation:

The samples were collected between the dates of 2021-07-03 and 2021-07-03

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330077

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330089

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.93.119.46 (Tuolumne Wild and Scenic River-37.93.119.46).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330090

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-04-30 and 2014-08-12

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330099

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.88.119.36 (Tuolumne Wild and Scenic River-37.88.119.36).

Temporal Representation:

The samples were collected between the dates of 2021-07-04 and 2021-07-04

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

332379

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:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 536TMRBDC (Tuolumne River ~0.6mi below Delaney Cr.).

Temporal Representation:

The samples were collected between the dates of 2022-08-31 and 2022-08-31

Environmental Conditions:

QAPP Information:

SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330138

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330148

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330153

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: ADVENTURESCIENTISTS-37.92.119.44 (Tuolumne Wild and Scenic River-37.92.119.44).

Temporal Representation:

The samples were collected between the dates of 2021-07-01 and 2021-07-01

Environmental Conditions:

QAPP Information:

Adventure Scientists 2020 QAPP

QAPP Information Reference(s):

Adventure Scientists - Adventure Scientists QAPP - Adventure Scientists (Volunteer)* - 402638

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330160

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330059

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160314, pH	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330136

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:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, Central Valley Region Sacramento River Basin and San Joaquin River Basin: pH should not be lower than 6.5 or higher than 8.5.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle


DECISION ID	160320	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Eight lines of evidence are available in the administrative record to assess this pollutant. Seventeen of the 17 samples exceed the guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the 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. Seventeen of 17 samples exceed the guideline, and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329649

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375310119231801 (TUOLUMNE R .45 MI BL DELANEY C NR TUOLUMNE MEADOWS).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329659

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375554119280301 (TUOLUMNE R BL RETURN C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329627

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375234119225900 (TUOLUMNE R AB BUDD C A TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-07 and 2014-07-07

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329600

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 10 of 10 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375258119225901 (DELANEY C BL DELANEY MEADOW NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-04-30 and 2014-08-12

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329593

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375433119250900 (TUOLUMNE RIVER BL CONNESS C NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329590

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-375556119275701 (RETURN C AB FOOTBRIDGE NR TUOLUMNE MEADOWS CA).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

330612

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, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 5

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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: 536TMRBDC (Tuolumne River ~0.6mi below Delaney Cr.).

Temporal Representation:

The samples were collected between the dates of 2022-08-31 and 2022-08-31

Environmental Conditions:

QAPP Information:

SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 160320, Alkalinity as CaCO3	Region 5
Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County)

LOE ID:

329634

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:

Water Board staff assessed USGS California Water Science Center data for Tuolumne River east of Hetch Hetchy Reservoir (Tuolumne County) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Alkalinity as CaCO3.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 5

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

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: USGS-11274790 (TUOLUMNE R A GRAND CYN OF TUOLUMNE AB HETCH HETCHY).

Temporal Representation:

The samples were collected between the dates of 2014-07-09 and 2014-07-09

Environmental Conditions:

QAPP Information:

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle

QAPP Information Reference(s):

QAPP for USGS Data Collected during the 2026 Integrated Report Cycle