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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):


DECISION ID	163652	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Phosphorus
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Name:	Lake Tahoe Nutrients/Sediment
TMDL Project Code:	198
Date TMDL Approved by USEPA:	08/22/2011
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for removal on the CWA section 303(d) List under sections 2.2 and 4.1 of the Listing Policy. Under 4.1 of the Policy, a minimum of one line of evidence is needed to assess listing status. Eleven lines of evidence are available in the administrative record to assess this pollutant. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. 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. Twenty of 25 samples exceeded the water quality objective and these exceed the allowable frequency listed in Table 4.1 of the Listing Policy. 4. The Lake Tahoe Nutrients/Sediment TMDL was approved by USEPA on 08/22/2011. 5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343232

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
3 of 3 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

4656

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343228

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
2 of 2 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River downstream of Lake Tahoe Blvd. (SLT-TR10-00)

Temporal Representation:

The samples were collected between the dates of 2012-05-12 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343225

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
2 of 3 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Washoe Meadows State Park (SLT-TR30-04)

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343224

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
0 of 3 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Christmas Valley (SLT-XMAS-01)

Temporal Representation:

The samples were collected between the dates of 2002-05-04 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343193

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Truckee River, Upper ~0.6mi below Grass Lk. Cr. (634TRU231)

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343222

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
8 of 9 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2002-05-04 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343248

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96682

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by Lahontan field staff collecting data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Surveys project. Data were collected on one day in August 2013. The recorded concentration was 0.0204 mg/L, which exceeds the site specific objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for phosphorous in the Upper Truckee River (below Christmas Valley), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.015 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

The Upper Truckee River is the largest tributary of Lake Tahoe. The watershed above Christmas Valley is National Forest land and includes a popular hiking/mountain biking/cross country skiing trail. Range livestock grazing under a U.S. Forest Service permit occurred in the watershed prior to 2000. The permit was subsequently revoked. The river is the largest tributary of Lake Tahoe in terms of flow. Due to the large size of Lake Tahoe and the long residence time of water in the lake (about 700 years), water quality in the Upper Truckee River does not directly influence the quality of the Truckee River downstream of Lake Tahoe. The lower portion of the rivers' watershed includes the urbanized areas of Meyers and South Lake Tahoe.

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343239

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163652, Phosphorus	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343244

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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


DECISION ID	163113	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	2-chloro-4-isopropylamino-6-amino-s-triazine
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	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 163113, 2-chloro-4-isopropylamino-6-amino-s-triazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342658

Pollutant:

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

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The California Department of Pesticide Regulation's online database includes data for the Upper Truckee River at South Lake Tahoe. These data were collected in May, June, July and August 1994 as part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program. The listed pesticide was not detected in any of the 4 samples

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 163113, 2-chloro-4-isopropylamino-6-amino-s-triazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342612

Pollutant:

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

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163129	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Alachlor
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 163129, Alachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342659

Pollutant:

Alachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163129, Alachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342613

Pollutant:

Alachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	162069	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Alkalinity as CaCO3
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Seventeen lines of evidence are available in the administrative record to assess this pollutant. Zero of the 21 samples exceed the guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 21 samples exceed the guideline and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337917

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337810

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

97350

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 5 monitoring site(s) (634S14257, 634S14261, 634S15274, 634S15277, 634S15298)

Temporal Representation:

The samples were collected between the dates of 2014-08-28 and 2015-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337822

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337935

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337829

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337837

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337843

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337848

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337977

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337972

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

97759

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Perennial Stream Surveys data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality standard for Alkalinity as CaCO3.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337897

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337981

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S11162 (Upper Truckee River 634011162 Status 2011).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338005

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338010

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162069, Alkalinity as CaCO3	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

337926

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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


DECISION ID	170428	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. 0 of 3 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 1 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170428, Ammonia	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338214

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170428, Ammonia	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338304

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 170428, Ammonia	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

98269

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater 2013

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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


DECISION ID	163097	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 163097, Azinphos-methyl (Guthion)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342615

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163097, Azinphos-methyl (Guthion)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342661

Pollutant:

Azinphos-methyl (Guthion)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The National Recommended Water Quality Criteria for Azinphos Methyl (Guthion) expressed as a 4-day average for the protection of freshwater aquatic life is a maximum of 0.01 ug/l.

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163117	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Benefin
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 163117, Benefin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342662

Pollutant:

Benefin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163117, Benefin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342616

Pollutant:

Benefin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163118	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Butylate
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 163118, Butylate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342617

Pollutant:

Butylate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Health Advisory for carbaryl as a drinking water level with a one in a million cancer risk is 0.04 mg/L.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163118, Butylate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342663

Pollutant:

Butylate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163088	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 163088, Carbaryl	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342618

Pollutant:

Carbaryl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Health Advisory for carbaryl as a drinking water level with a one in a million cancer risk is 0.04 mg/L.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163088, Carbaryl	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342664

Pollutant:

Carbaryl

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA National Recommended Aquatic Life criteria pursuant to Section 304(a) of the Clean Water Act for Carbaryl is 2.1 ug/L.

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163089	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Carbofuran
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 163089, Carbofuran	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342619

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Carbofuran incorporated by reference in the Water Quality Control Plan, Lahontan Region is 18 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163089, Carbofuran	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342665

Pollutant:

Carbofuran

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163090	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Chlorpyrifos
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 163090, Chlorpyrifos	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342620

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163090, Chlorpyrifos	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342666

Pollutant:

Chlorpyrifos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The freshwater criterion continuous concentration to protect aquatic organisms is 0.014 ug/L (Siepmann and Finlayson 2000).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163119	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Cyanazine
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 163119, Cyanazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342667

Pollutant:

Cyanazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163119, Cyanazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342621

Pollutant:

Cyanazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	170429	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 170429, DDE (Dichlorodiphenyldichloroethylene)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342622

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The DDE(4,4') criteria for the protection of human health from the consumption of water and organisms is 0.00059 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

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:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 170429, DDE (Dichlorodiphenyldichloroethylene)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342668

Pollutant:

DDE (Dichlorodiphenyldichloroethylene)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163092	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Diazinon
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 163092, Diazinon	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342670

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163092, Diazinon	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342624

Pollutant:

Diazinon

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163093	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Dieldrin
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 163093, Dieldrin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342625

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Dieldrin criteria for the protection of human health from the consumption of water and organisms is 0.00014 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163093, Dieldrin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342671

Pollutant:

Dieldrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The dieldrin criterion continuous concentration (expressed as a 4-day average) to protect aquatic life in freshwater is 0.056 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163131	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Dimethomorph
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 163131, Dimethomorph	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342611

Pollutant:

Dimethomorph

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163131, Dimethomorph	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342657

Pollutant:

Dimethomorph

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for Dimethomorph is the USEPA Aquatic Life Benchmark of 107 ug/L for a fish (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163095	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Dyfonate (Fonofos or Fonophos)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	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 163095, Dyfonate (Fonofos or Fonophos)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342627

Pollutant:

Dyfonate (Fonofos or Fonophos)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163095, Dyfonate (Fonofos or Fonophos)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342673

Pollutant:

Dyfonate (Fonofos or Fonophos)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163096	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	EPTC (Eptam, s-ethyl dipropylthiocarbamate)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	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 163096, EPTC (Eptam, s-ethyl dipropylthiocarbamate)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342674

Pollutant:

EPTC (Eptam, s-ethyl dipropylthiocarbamate)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163096, EPTC (Eptam, s-ethyl dipropylthiocarbamate)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342628

Pollutant:

EPTC (Eptam, s-ethyl dipropylthiocarbamate)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA safe lifetime exposure limit in drinking water for EPTC, calculated using the IRIS Reference Dose, is 180 ug/L.

Guideline Reference:

IRIS Reference Summary (Various Pollutants)

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163120	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Ethalfluralin
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 163120, Ethalfluralin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342629

Pollutant:

Ethalfluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163120, Ethalfluralin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342675

Pollutant:

Ethalfluralin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163121	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Ethoprop
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 163121, Ethoprop	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342630

Pollutant:

Ethoprop

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163121, Ethoprop	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342676

Pollutant:

Ethoprop

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163099	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Lindane/gamma Hexachlorocyclohexane (gamma-HCH)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	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 163099, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342678

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163099, Lindane/gamma Hexachlorocyclohexane (gamma-HCH)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342632

Pollutant:

Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The BCH, Gamma (Lindane) criterion for the protection of human health from the consumption of water and organisms is 0.019 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163100	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Linuron
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 163100, Linuron	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342679

Pollutant:

Linuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163100, Linuron	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342633

Pollutant:

Linuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163101	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Malathion
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 163101, Malathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342680

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163101, Malathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342634

Pollutant:

Malathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163102	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 163102, Methyl Parathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342681

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The California Department of Fish and Game instantaneous aquatic life criterion for methyl parathion is 0.08 ug/L.

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163102, Methyl Parathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342635

Pollutant:

Methyl Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Health Advisory for lifetime exposure to Parathion, Methyl as a drinking water level is a concentration of 1 ug/L

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163122	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Metolachlor
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 163122, Metolachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342682

Pollutant:

Metolachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for metolachlor is the USEPA Aquatic Life Benchmark of 1 ug/L for an invertebrate (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163122, Metolachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342636

Pollutant:

Metolachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Water Quality Advisory for Metolachlor is 0.044 mg/L. (USEPA Water Quality Advisory, March 1986, p. 15)

Guideline Reference:

Water Quality Health Advisory document for Metolachlor

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163123	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Metribuzin
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 163123, Metribuzin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342683

Pollutant:

Metribuzin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for metribuzin is the USEPA Aquatic Life Benchmark of 8.1 ug/L for a nonvascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163123, Metribuzin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342637

Pollutant:

Metribuzin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163124	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Napropamide
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 163124, Napropamide	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342685

Pollutant:

Napropamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for Napropamide is the USEPA Aquatic Life Benchmark of 350 ug/L for a vascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163124, Napropamide	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342639

Pollutant:

Napropamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	101525	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. 0 of 1 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 if 1 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 101525, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

97644

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for nitrate + nitrite (as N) that is incorporated by reference in the Water Quality Control Plan, Lahontan Region is 10.0 mg/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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


DECISION ID	170431	Region 6
Truckee River, Upper (below Christmas Valley)

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 170431, Nitrogen, Nitrate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338939

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 45000 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2010-05-22 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170431, Nitrogen, Nitrate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338959

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 45000 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2001-06-02

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170431, Nitrogen, Nitrate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338938

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 45000 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2011-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170431, Nitrogen, Nitrate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338931

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 45000 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2002-05-04 and 2012-05-12

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170431, Nitrogen, Nitrate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

338947

Pollutant:

Nitrate as Nitrate (NO3)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Nitrate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 45000 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2002-05-04

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634


DECISION ID	163104	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 163104, Parathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342686

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163104, Parathion	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342640

Pollutant:

Parathion

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163125	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:	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 163125, Pendimethalin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342642

Pollutant:

Pendimethalin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA expected safe lifetime exposure limit in drinking water for Pendimethalin, calculated using the IRIS Reference Dose, is 280 ug/L. This was calculated assuming 70 kg body weight, 2 liters/day water consumption, 20% relative source contribution from drinking water, and 0.04 mg/kg/day as the reference dose.

Guideline Reference:

IRIS Reference Summary (Various Pollutants)

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163125, Pendimethalin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342688

Pollutant:

Pendimethalin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for pendimethalin is the USEPA Aquatic Life Benchmark of 5.2 ug/L for a nonvascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163130	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Permethrin
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 163130, Permethrin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342643

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163130, Permethrin	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342689

Pollutant:

Permethrin

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Aquatic life should not be affected unacceptably if the 4-day average concentration of Permethrin, does not exceed 0.002 ug/L more than once every three years on the average (UC Davis Aquatic Life Criterion).

Guideline Reference:

Aquatic life water quality criteria derived via the UC Davis method: ll. Pyrethroid insecticides. Reviews of Environmental Contamination and Toxicology 216:51-103.

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163126	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Phorate
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 163126, Phorate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342690

Pollutant:

Phorate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for an invertebrate (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163126, Phorate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342644

Pollutant:

Phorate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163105	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Prometon (Prometone)
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 163105, Prometon (Prometone)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342645

Pollutant:

Prometon (Prometone)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Health Advisory for 10 day exposure of a 10 kg-Child to Prometon as a drinking water level is a concentration of 0.02 mg/L.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163105, Prometon (Prometone)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342691

Pollutant:

Prometon (Prometone)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for phorate is the USEPA Aquatic Life Benchmark of 0.21 ug/L for an invertebrate (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163106	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	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 163106, Pronamide	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342646

Pollutant:

Pronamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Health Advisory for Pronamide as a drinking water level with a one in a million cancer risk is 0.001 mg/L.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163106, Pronamide	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342692

Pollutant:

Pronamide

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163107	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Propanil (DCPA mono- and di-acid degrad)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	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 163107, Propanil (DCPA mono- and di-acid degrad)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342694

Pollutant:

Propanil (DCPA mono- and di-acid degrad)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for propanil (DCPA mono- and di-acid degrad) is the USEPA Aquatic Life Benchmark of 9.1 ug/L for a fish (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163107, Propanil (DCPA mono- and di-acid degrad)	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342648

Pollutant:

Propanil (DCPA mono- and di-acid degrad)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Documentation of water quality criteria for individual pollutants in Lines of Evidence for multipollutant datasets is not required, except for pollutants that exceed a standard or criterion. There are no state or federal water quality standards or criteria for pebulate, the only detectable pollutant in this dataset. The Lahontan Basin Plan includes a narrative water quality objective for pesticides in surface waters that provides that: Pesticide concentrations, individually or collectively, shall not exceed the lowest detectable leves, using the most recent detection procedures available.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163115	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Propargite
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 163115, Propargite	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342649

Pollutant:

Propargite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163115, Propargite	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342695

Pollutant:

Propargite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for propargite is the USEPA Aquatic Life Benchmark of 7 ug/L for an invertebrate (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163108	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Simazine
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 163108, Simazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342696

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for simazine is the USEPA Aquatic Life Benchmark of 6 ug/L for a nonvascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163108, Simazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342650

Pollutant:

Simazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Simazine incorporated by reference in the Water Quality Control Plan, Lahontan Region is 4 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	170432	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Twenty-five lines of evidence are available in the administrative record to assess this pollutant. 0 of 70 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 70 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 26 samples are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list 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 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340557

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340372

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340318

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340430

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340455

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340361

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340641

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S11162 (Upper Truckee River 634011162 Status 2011).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340330

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340391

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340616

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-02 (Upper Truckee River upstream of Elks Club).

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340577

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340317

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340528

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

97782

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

98459

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 5 monitoring site(s) (634S14257, 634S14261, 634S15274, 634S15277, 634S15298)

Temporal Representation:

The samples were collected between the dates of 2014-08-28 and 2015-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340524

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340363

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340650

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-00 (Upper Truckee River downstream of Lake Tahoe Blvd.).

Temporal Representation:

The samples were collected between the dates of 2008-05-10 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340591

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340406

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340483

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340530

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340584

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340618

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170432, Specific Conductivity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340432

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-SIDE-01 (Upper Truckee River Side Channel near 1080 Lodi Ave.).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2003-05-10

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634


DECISION ID	163653	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. One of the 4 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the 4 samples exceed the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163653, Sulfates	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343310

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 1 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 163653, Sulfates	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343316

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 1 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163653, Sulfates	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343319

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed USFS Management Indicator Species - Streams data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Sulfate

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Sulfate in this water body is 1 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Truckee River, Upper ~0.6mi below Grass Lk. Cr. (634TRU231)

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 163653, Sulfates	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96684

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by Lahontan field staff collecting data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Surveys project. Data were collected on one day in August 2013. The recorded concentration was 1.08 mg/L, which exceeds the site specific objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for sulfates in the Upper Truckee River (below Christmas Valley), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 1.0 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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


DECISION ID	163110	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Terbufos
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 163110, Terbufos	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342699

Pollutant:

Terbufos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for terbufos is the USEPA Aquatic Life Benchmark of 0.03 ug/L for an invertebrate (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163110, Terbufos	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342653

Pollutant:

Terbufos

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	171851	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 171851, Thiobencarb	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342654

Pollutant:

Thiobencarb/Bolero

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Thiobencarb incorporated by reference in the Water Quality Control Plan, Lahontan Region is 70 ug/L (Water Quality Control

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171851, Thiobencarb	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342700

Pollutant:

Thiobencarb/Bolero

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for thiobencarb is the USEPA Aquatic Life Benchmark of 1 ug/L for an invertebrate (chronic).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163128	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Triallate
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 163128, Triallate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342655

Pollutant:

Triallate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163128, Triallate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342701

Pollutant:

Triallate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for triallate is the USEPA Aquatic Life Benchmark of 14 ug/L for an invertebrate (chronic).

Guideline Reference:

Field from the Section 319h Grants for the 2026 Integrated Report in Region 6

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	162068	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Fourteen lines of evidence are available in the administrative record to assess this pollutant. Sixteen of the 113 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Sixteen of the 113 samples exceed the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340871

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Upper Truckee Marsh 319 Monitoring data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 8 of 24 samples exceeded the water quality threshold for Turbidity.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) based upon drinking water standards specified in Title 22 of the California Code of Regulations. The Lahontan Basin Plan also has regionwide turbidity objective for other beneficial uses that states: Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10%.

Objective/Criterion Reference:

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

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Lahontan Basin Plan's 'Chemical Constituents' objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment.

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRUSGS (Upper Truckee River at USGS Gage).

Temporal Representation:

The samples were collected between the dates of 2014-11-17 and 2016-05-13

Environmental Conditions:

QAPP Information:

Upper Truckee Marsh 319 QAPP

QAPP Information Reference(s):

Lahontan Water Board - UpperTruckeeMarsh319QAPP - Upper Truckee Marsh 319 Monitoring - 402635

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340972

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-02 (Upper Truckee River upstream of Elks Club).

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340906

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340839

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340880

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340874

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2010-05-22 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340974

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

98266

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Lahontan Basin Plan's \Chemical Constituents\" objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment. "

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340913

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340855

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340859

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-SIDE-01 (Upper Truckee River Side Channel near 1080 Lodi Ave.).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2004-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

98967

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed NWIS data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 6 of 43 samples exceeded the water quality standard for Turbidity.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the USGS National Water Information System.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (USGS-10336610)

Temporal Representation:

The samples were collected between the dates of 2014-01-09 and 2016-09-19

Environmental Conditions:

QAPP Information:

QAPP not required for federal data

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 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340808

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-00 (Upper Truckee River downstream of Lake Tahoe Blvd.).

Temporal Representation:

The samples were collected between the dates of 2009-05-16 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162068, Turbidity	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340869

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634


DECISION ID	162067	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

129633

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:

0 of 0 samples exceeded the water quality standard for pH. Although pH data does exist for this waterbody, the objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality standards could not be made.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide objective for pH states: \In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.\""

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

129811

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 5 monitoring site(s) (634S14257, 634S14261, 634S15274, 634S15277, 634S15298)

Temporal Representation:

The samples were collected between the dates of 2014-08-28 and 2015-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

129577

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339827

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 TRPA Tahoe Ambient Monitoring data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide objective for pH states: 'In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis.'

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339762

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339771

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 9 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339774

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339538

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339711

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339562

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-00 (Upper Truckee River downstream of Lake Tahoe Blvd.).

Temporal Representation:

The samples were collected between the dates of 2008-05-10 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339889

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340210

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340055

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-SIDE-01 (Upper Truckee River Side Channel near 1080 Lodi Ave.).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2003-05-10

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339988

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 14 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340076

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340012

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340018

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340099

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-02 (Upper Truckee River upstream of Elks Club).

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339863

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 USFS Management Indicator Species - Streams data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340181

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339868

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339945

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339876

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 from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339934

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-SIDE-01 (Upper Truckee River Side Channel near 1080 Lodi Ave.).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2003-05-10

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340176

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339875

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339583

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339746

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 14 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339747

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339816

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339607

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339776

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339708

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339712

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339556

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340128

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339890

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339977

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340218

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 6 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-00 (Upper Truckee River downstream of Lake Tahoe Blvd.).

Temporal Representation:

The samples were collected between the dates of 2008-05-10 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339904

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340220

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 2 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-02 (Upper Truckee River upstream of Elks Club).

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340067

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Truckee River, Upper (below Christmas Valley) to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for pH. The objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality thresholds could not be made.

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

340070

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339998

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339999

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339877

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339663

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

Line of Evidence (LOE) for Decision ID 162067, pH	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

129805

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 5 monitoring site(s) (634S14257, 634S14261, 634S15274, 634S15277, 634S15298)

Temporal Representation:

The samples were collected between the dates of 2014-08-28 and 2015-09-18

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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


DECISION ID	171792	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Benthic Community Effects
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Benthic Community Effects are being considered for placement on the CWA section 303(d) List under sections 3.9 of the Listing Policy. Under section 3.9, additional lines of evidence (LOEs) associating the Benthic Community Effects decision with a water or sediment concentration of pollutants other than benthic-macroinvertebrate bioassessment or habitat assessment LOEs are necessary to place a water body on the 303(d) List for Benthic Community Effects. 48 line(s) of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. 8 of 26 benthic-macroinvertebrate samples exceed the California Stream Condition Index (CSCI) impairment threshold. Additionally, there are associated pollutant impairments on the waterbody (including but not necessarily limited to Chloride, Phosphorus, and Total Nitrogen as N). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 8 of 26 benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. Therefore, this water body is exceeding the water quality threshold for the protection of the WARM and/or COLD beneficial use. 4. Pursuant to section 3.9 of the Listing Policy, the water segment has associated pollutant(s) samples that exceed water quality objectives. 5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352814

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S15298 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.544905 to 0.544905 .

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S15298 (634S15298 Upper Truckee River Status 2015).

Temporal Representation:

Samples were collected from 2015-08-19 to 2015-08-19.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352810

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S15277 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.838288 to 0.838288 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S15277 (634S15277 Upper Truckee River Status 2015).

Temporal Representation:

Samples were collected from 2015-08-04 to 2015-08-04.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342741

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342761

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
0 of 5 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2020-05-30

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342779

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Washoe Meadows State Park (SLT-TR30-04)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342747

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Truckee River, Upper ~0.6mi below Grass Lk. Cr. (634TRU231)

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342792

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96681

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by Lahontan field staff collecting data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Surveys project. Data were collected on one day in August 2013. The recorded concentration was 8.1 mg/L, which exceeds the site specific objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for chloride in the Upper Truckee River (below Christmas Valley), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 4.0 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342773

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
1 of 2 samples exceeded the water quality threshold for Chloride

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342757

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
1 of 6 samples exceeded the water quality threshold for Chloride

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2020-05-30

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

4655

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343120

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Christmas Valley (SLT-XMAS-01)

Temporal Representation:

The samples were collected between the dates of 2021-05-15 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343146

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343132

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343106

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
1 of 5 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343123

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343087

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data to determine beneficial use support and results are as follows:
0 of 4 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339379

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343232

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343193

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Truckee River, Upper ~0.6mi below Grass Lk. Cr. (634TRU231)

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343248

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

4656

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Evaluation Guideline:

Unspecified

Guideline Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343228

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River downstream of Lake Tahoe Blvd. (SLT-TR10-00)

Temporal Representation:

The samples were collected between the dates of 2012-05-12 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343224

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Christmas Valley (SLT-XMAS-01)

Temporal Representation:

The samples were collected between the dates of 2002-05-04 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343225

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Washoe Meadows State Park (SLT-TR30-04)

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343244

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343222

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2002-05-04 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343239

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Phosphorus as P in this water body is 0.015 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96682

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

132802

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

The CSCI scores from this site are:
0.840750977
1.020952627 (this sample was averaged from two samples taken at the same station on the same day)
0.423512573
0.846852566
0.567070711

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

SWAMP Data:

Water Quality Objective/Criterion:

All waters shall be maintained free of toxic substances in concentrations that are lethal to or that produce significant alterations in population or community ecology or receiving water biota. In addition, the health and life history characteristics of aquatic organisms in waters affected by controllable water quality factors shall not differ significantly from those for the same waters in areas unaffected by controllable water quality factors.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

Samples collected at the following stations:
634S14257
634S14261
634S15274
634S15277
634S15298

Temporal Representation:

Samples collected on:
8/28/2014
9/3/2014
9/18/2015
8/4/2015
8/19/2015

Environmental Conditions:

QAPP Information:

QAPP for TRPA Tahoe Ambient Monitoring

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96383

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

The site had a CSCI score of 0.908256681. There is insufficient information to determine if this site is not exceeding the water quality objective for the aquatic life beneficial use, a minimum of two benthic-macroinvertebrate samples are required to determine beneficial use attainment. Additionally, this water body passed several screening criteria and was identified as a reference water body for the purposes of developing the CSCI. Reference sites where human disturbance is absent or minimal are used to set benchmark expectations for healthy streams. A large set of nearly 600 reference sites representing the broad diversity of natural stream types found across California was used to develop the CSCI.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

Collected at site 634PS0131

Temporal Representation:

Collected on:

8/20/2013

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Perennial Stream Surveys

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352803

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S14261 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.03496 to 1.03496 .

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14261 (Upper Truckee River 634S14261 Status 2014).

Temporal Representation:

Samples were collected from 2014-09-03 to 2014-09-03.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352835

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S17341 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.17125 to 1.17125 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

Samples were collected from 2017-10-02 to 2017-10-02.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352877

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634TRU231 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.858105063 to 0.858105063 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

Samples were collected from 2020-07-22 to 2020-07-22.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352861

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634TPA041 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.03705 to 1.03705 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

Samples were collected from 2018-07-05 to 2018-07-05.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352809

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S15274 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.426473 to 0.426473 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S15274 (634S15274 Upper Truckee River Status 2015).

Temporal Representation:

Samples were collected from 2015-09-18 to 2015-09-18.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352880

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634UTR002 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.779414981 to 0.779414981 .

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

Samples were collected from 2019-08-12 to 2019-08-12.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352881

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634UTR006 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.06416 to 1.06416 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

Samples were collected from 2017-08-21 to 2017-08-21.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352864

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634TPA085 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.13979 to 1.13979 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

Samples were collected from 2018-07-31 to 2018-07-31.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352847

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S18369 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.03001 to 1.03001 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

Samples were collected from 2018-09-18 to 2018-09-18.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352792

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S10114 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.733981 to 0.733981 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

Samples were collected from 2018-09-25 to 2018-09-25.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352801

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S14257 to determine beneficial use support and the results are as follows: 0 of 2 samples exceeded the water quality standard. CSCI scores were from 0.847382 to 1.02777 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

Samples were collected from 2014-08-28 to 2018-07-12.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352870

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634TPB141 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.05194 to 1.05194 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

Samples were collected from 2017-08-10 to 2017-08-10.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352793

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S11162 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.844231 to 0.844231 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S11162 (Upper Truckee River 634011162 Status 2011).

Temporal Representation:

Samples were collected from 2017-10-09 to 2017-10-09.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352794

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S13242 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.735089 to 0.735089 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

Samples were collected from 2017-08-30 to 2017-08-30.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352852

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634S18377 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.962976 to 0.962976 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

Samples were collected from 2018-07-16 to 2018-07-16.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352857

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634TPA021 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.15543 to 1.15543 .

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

Samples were collected from 2018-07-17 to 2018-07-17.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 171792, Benthic Community Effects	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

352883

Pollutant:

Benthic-Macroinvertebrate Bioassessments

LOE Subgroup:

Population/Community Degradation

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Benthic macroinvertebrate surveys

Data Used to Assess Water Quality:

Water Board staff assessed data for 634UTRBAP to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.769988264 to 0.769988264 .

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

Samples were collected from 2019-08-12 to 2019-08-12.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.


DECISION ID	163651	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Chloride
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
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. 5 of the 18 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the 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. 5 of 18 samples exceed the objective and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96681

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by Lahontan field staff collecting data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Surveys project. Data were collected on one day in August 2013. The recorded concentration was 8.1 mg/L, which exceeds the site specific objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342779

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Washoe Meadows State Park (SLT-TR30-04)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342773

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342792

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342741

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
1 of 1 samples exceeded the water quality threshold for Chloride

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342761

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2020-05-30

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342757

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2020-05-30

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 163651, Chloride	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342747

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Chloride in this water body is 4 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Truckee River, Upper ~0.6mi below Grass Lk. Cr. (634TRU231)

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.


DECISION ID	170435	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Nitrogen
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Eleven lines of evidence are available in the administrative record to assess this pollutant. Two of the 13 samples with a total fraction exceed the objective; 1 of 5 samples with an unrecorded fraction exceed the objective; and 0 of 1 samples with a dissolved fraction exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of 13 samples exceed the objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

96683

Pollutant:

Nitrogen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data were collected by Lahontan field staff collecting data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Surveys project. Data were collected on one day in August 2013. The recorded concentration was 0.0831 mg/L, which attains the site specific objective.

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for nitrogen in the Upper Truckee River (below Christmas Valley), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.19 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected in one location, 634PS0131, which is found at the end of Woodchuck Court approx. 0.3 miles downstream of Portal Drive in Christmas Valley.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

QAPP Information:

Data were collected in accordance with the SWAMP QAPP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343087

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343101

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Echo Creek at Upper Truckee River Confluence (SLT-ECHO-00)

Temporal Representation:

The samples were collected between the dates of 2010-05-22 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343118

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Elks Club Drive (SLT-TR20-01)

Temporal Representation:

The samples were collected between the dates of 2010-05-22 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343120

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Christmas Valley (SLT-XMAS-01)

Temporal Representation:

The samples were collected between the dates of 2021-05-15 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343106

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River below Lake Tahoe Boulevard (SLT-TR10-01)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343132

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River, Barton @ airport (upper) (634UTR002)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343123

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River upstream of Elks Club (SLT-TR20-02)

Temporal Representation:

The samples were collected between the dates of 2016-05-14 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343119

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River at Washoe Meadows State Park (SLT-TR30-04)

Temporal Representation:

The samples were collected between the dates of 2013-05-11 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343091

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River downstream of Lake Tahoe Blvd. (SLT-TR10-00)

Temporal Representation:

The samples were collected between the dates of 2013-05-11 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 170435, Nitrogen	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

343146

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP RWB6 Monitoring data to determine beneficial use support and results are as follows:
0 of 1 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total in this water body is 0.19 (mg/L), (as a Mean).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Upper Truckee River blw airport (634UTRBAP)

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat, WQ from the USFS Management Indicator Species for the 2026 Integrated Report in Region 6


DECISION ID	162066	Region 6
Truckee River, Upper (below Christmas Valley)

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
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. Thirty-eight lines of evidence are available in the administrative record to assess this parameter: 25 which assess dissolved oxygen concentration data and 13 which assess dissolved oxygen percent saturation data. Zero of 64 samples are below the objective for minimum dissolved oxygen concentration. Thirteen of 13 samples are below the objective for minimum dissolved oxygen percent saturation. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification 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. Thirteen of 13 samples are below the objective for minimum dissolved oxygen percent saturation 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 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339279

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

For waters with the beneficial uses of COLD, COLD with SPWN, WARM, and WARM with SPWN, the minimum dissolved oxygen concentration shall not be less than that specified in Table 3-6. (Water Quality Control Plan, Lahontan Region)

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRU231 (Truckee River, Upper ~0.6mi below Grass Lk. Cr.).

Temporal Representation:

The samples were collected between the dates of 2020-07-22 and 2020-07-22

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339468

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S11162 (Upper Truckee River 634011162 Status 2011).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339486

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339495

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339501

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339333

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339354

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339432

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339365

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339379

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339454

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339456

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339166

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA085 (Truckee River 634011085 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-31 and 2018-07-31

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

130119

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634S15277)

Temporal Representation:

The samples were collected between the dates of 2015-08-04 and 2015-08-04

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

130113

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Tahoe Regional Planning Agency (TRPA) Tahoe Ambient Monitoring program.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 3 monitoring site(s) (634S14257, 634S14261, 634S15277)

Temporal Representation:

The samples were collected between the dates of 2014-08-28 and 2015-08-04

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

130127

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Perennial Stream Surveys.

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634PS0131)

Temporal Representation:

The samples were collected between the dates of 2013-08-20 and 2013-08-20

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339288

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA021 (Upper Truckee River 634011021 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-17 and 2018-07-17

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339457

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339168

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18369 (634S18369 Upper Truckee River Status 2018).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339037

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTRBAP (Upper Truckee River blw airport).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

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

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339044

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR002 (Upper Truckee River, Barton @ airport (upper)).

Temporal Representation:

The samples were collected between the dates of 2019-08-12 and 2019-08-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339049

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-01 (Upper Truckee River at Elks Club Drive).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339185

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-01 (Upper Truckee River below Lake Tahoe Boulevard).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339058

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-XMAS-01 (Upper Truckee River at Christmas Valley).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 and 2021-05-15

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339293

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR20-02 (Upper Truckee River upstream of Elks Club).

Temporal Representation:

The samples were collected between the dates of 2015-05-16 and 2016-05-14

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339208

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S11162 (Upper Truckee River 634011162 Status 2011).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339209

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S13242 (Upper Truckee River 634013242 Status 2013).

Temporal Representation:

The samples were collected between the dates of 2017-08-30 and 2017-08-30

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339305

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S14257 (Upper Truckee River 634S14257 Status 2014).

Temporal Representation:

The samples were collected between the dates of 2018-07-12 and 2018-07-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339223

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634UTR006 (Upper Truckee River, Celio lower).

Temporal Representation:

The samples were collected between the dates of 2017-08-21 and 2017-08-21

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339228

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPA041 (Upper Truckee River 634011041 Trend Panel A).

Temporal Representation:

The samples were collected between the dates of 2018-07-05 and 2018-07-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339092

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S10114 (Upper Truckee River 634010114 Status 2010).

Temporal Representation:

The samples were collected between the dates of 2018-09-25 and 2018-09-25

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339255

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S17341 (634S17341 Upper Truckee River Status 2017).

Temporal Representation:

The samples were collected between the dates of 2017-10-02 and 2017-10-02

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339117

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634S18377 (634S18377 Upper Truckee River Status 2018).

Temporal Representation:

The samples were collected between the dates of 2018-07-16 and 2018-07-16

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339121

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-ECHO-00 (Echo Creek at Upper Truckee River Confluence).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2010-05-22

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339127

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR30-04 (Upper Truckee River at Washoe Meadows State Park).

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2014-05-17

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339269

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat from the Tahoe Regional Planning Authority for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 634TPB141 (Upper Truckee River 634010141 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-08-10 and 2017-08-10

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339270

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-SIDE-01 (Upper Truckee River Side Channel near 1080 Lodi Ave.).

Temporal Representation:

The samples were collected between the dates of 2003-05-10 and 2003-05-10

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634

Line of Evidence (LOE) for Decision ID 162066, Oxygen, Dissolved	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

339139

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:

Field, WQ from the Truckee Tahoe Snapshot Day for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SLT-TR10-00 (Upper Truckee River downstream of Lake Tahoe Blvd.).

Temporal Representation:

The samples were collected between the dates of 2008-05-10 and 2013-05-11

Environmental Conditions:

QAPP Information:

Tahoe Truckee Snapshot QAPP

QAPP Information Reference(s):

Lahontan Water Board - TahoeTruckeeSnapshotQAPP - League to Save Lake Tahoe Truckee Tahoe Snapshot D - 402634


DECISION ID	163087	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant, one that assesses available data for the MUN use and one that assesses for the COLD use. Zero of 4 samples exceed the guideline for MUN and 0 of 4 samples exceed the guideline for COLD. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 4 samples exceed the guideline for MUN and 0 of 4 samples exceed the guideline for COLD and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163087, Atrazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342614

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for atrazine incorporated by reference in the Water Quality Control Plan, Lahontan Region is 1 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163087, Atrazine	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342660

Pollutant:

Atrazine

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163091	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant, one that assesses the available data for the COLD use and one that assesses for the MUN use. Zero of 4 samples exceed the guideline for COLD and 0 of 4 samples exceed the guideline for MUN. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 4 samples exceed the guideline for COLD and 0 of 4 samples exceed the guideline for MUN and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163091, Dacthal	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342623

Pollutant:

Dacthal

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The USEPA Lifetime Health advisory level for Dacthal is 0.07 mg/L.

Guideline Reference:

2012 Edition of the Drinking Water Standards and Health Advisories

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163091, Dacthal	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342669

Pollutant:

Dacthal

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for Dacthal is the USEPA Aquatic Life Benchmark of >11000 ug/L for a nonvascular plant (acute) and vascular plant (acute). The benchmark was derived from a greater-than value (for example, > 265,000) and may overestimate toxicity.

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163094	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163094, Disulfoton	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342672

Pollutant:

Disulfoton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163094, Disulfoton	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342626

Pollutant:

Disulfoton

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163098	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163098, Hexachlorobenzene/ HCB	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342631

Pollutant:

Hexachlorobenzene/ HCB

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Hexachlorobenzene criteria for the protection of human health from the consumption of water and organisms is 0.00075 ug/L (California Toxics Rule, 2000).

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163098, Hexachlorobenzene/ HCB	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342677

Pollutant:

Hexachlorobenzene/ HCB

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163103	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163103, Molinate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342684

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163103, Molinate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342638

Pollutant:

Molinate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The California Maximum Contaminant Level for Molinate incorporated by reference in the Water Quality Control Plan, Lahontan Region is 20 ug/L (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163116	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163116, Pebulate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342687

Pollutant:

Pebulate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for pebulate is the USEPA Aquatic Life Benchmark of 230 ug/L for a nonvascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163116, Pebulate	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342641

Pollutant:

Pebulate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163127	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163127, Propachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342647

Pollutant:

Propachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163127, Propachlor	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342693

Pollutant:

Propachlor

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163114	Region 6
Truckee River, Upper (below Christmas Valley)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163114, Tebuthiuron	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342651

Pollutant:

Tebuthiuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163114, Tebuthiuron	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342697

Pollutant:

Tebuthiuron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for tebuthiuron is the USEPA Aquatic Life Benchmark of 50 ug/L for a nonvascular plant (acute).

Guideline Reference:

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

Spatial Representation:

One station, Upper Truckee River at South Lake Tahoe, was sampled.

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

The data meet USGS quality assurance requirements.

QAPP Information Reference(s):


DECISION ID	163109	Region 6
Truckee River, Upper (below Christmas Valley)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant, one that assesses available data for the COLD use and one that assesses for the MUN use. Zero of 4 samples exceed the guideline for COLD and 0 of 4 samples exceed the guideline for MUN. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 4 samples exceed the guideline for COLD and 0 of 4 samples exceed the guideline for MUN and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163109, Terbacil	Region 6
Truckee River, Upper (below Christmas Valley)

LOE ID:

342698

Pollutant:

Terbacil

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

The evaluation guideline for terbacil is the USEPA Aquatic Life Benchmark of 11 ug/L for a nonvascular plant (acute).

Guideline Reference: