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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Trout Creek (above Hwy 50)
Water Body ID:	CAR6341003120000220171341
Water Body Type:	River & Stream


DECISION ID	170485	Region 6
Trout Creek (above Hwy 50)

Pollutant:	Indicator Bacteria
Final Listing Decision:	Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Delist from 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Reason for Delisting:	Applicable WQS attained; due to change in WQS
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	(The decision is called "delist" due to database rules, since this pollutant was listed in the past. The action the Board is taking in this cycle is actually "do not list") 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. Seven lines of evidence are available in the administrative record to assess this pollutant. 2 of the 53 samples exceed the Statistical Threshold Value water quality objective for E. coli; 0 of 59 samples exceed the geomean water quality objective for E. coli. 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. 2 of the 53 samples exceed the Statistical Threshold Value water quality objective for E. coli; 0 of 59 samples exceed the geomean water quality objective for E. coli 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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

100014

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed RWB6_BACT_Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 2 of the 33 samples exceeded the Statistical Threshold Value (STV) water quality standard for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective applicable to all waters, except Lake Tahoe, where the salinity is less than 10 parts per thousand (ppth) 95 percent or more of the time is a STATISTICAL THRESHOLD VALUE (STV) of 320 cfu/100 mL not to be exceeded more than 10 percent of the time (calculated monthly).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 3 monitoring site(s), station(s): 634CE0146, 634TRTB03, 634TRTB10

Temporal Representation:

The samples were collected between the days of 2010-08-31 and 2015-08-25 .

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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4645

Pollutant:

Pathogens

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

336792

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 0 of the 8 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): SLT-TROU-02 (Trout Creek at Grinding Stone).

Temporal Representation:

The samples were collected between the days of 2013-05-11 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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

336802

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

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:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): SLT-TR15-02 (Trout Creek at Blackbart Bridge).

Temporal Representation:

The samples were collected between the days of 2014-05-17 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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

336821

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

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:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): SLT-TROU-03 (Trout Creek at Saxon Creek Confluence).

Temporal Representation:

The samples were collected between the days 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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

336800

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 0 of the 1 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

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:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): SLT-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the days 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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

100167

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed RWB6_BACT_Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 0 of the 59 samples exceeded the geomean water quality standard for E. coli. This is a six week rolling geomean that is calculated weekly.

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 3 monitoring site(s), station(s): 634CE0146, 634TRTB03, 634TRTB10

Temporal Representation:

The samples were collected between the days of 2010-08-31 and 2015-08-25 .

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 170485, Indicator Bacteria	Region 6
Trout Creek (above Hwy 50)

LOE ID:

336788

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and the results are as follows: 0 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

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:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): SLT-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

The samples were collected between the days of 2014-05-17 and 2015-05-16 .

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	170489	Region 6
Trout Creek (above Hwy 50)

Pollutant:	Nitrogen
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by 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:	08/16/2011
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. 303(d) listing decisions made prior to 2006 were not held in an assessment database. Regional Board conclusion: This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. Two lines of evidence are available in the administrative record to assess this pollutant. Five of the 13 samples exceed the water quality objective. Trout Creek (above Hwy 50) is a tributary to Lake Tahoe. The Lake Tahoe TMDL includes an implementation plan that identifies actions that resource management agencies, Lake Tahoe municipalities (El Dorado and Placer Counties, City of South Lake Tahoe) and California Department of Transportation (CalTrans) must take to reduce inputs of nutrients (nitrogen and phosphorus) and fine sediment. On the ground efforts required by the Lake Tahoe TMDL that focus on (1) stabilizing disturbed areas within the forested uplands, (2) restoring eroding stream channels, and (3) managing and treating urban uplands (e.g. street sweeping, installing and maintaining infiltration and stormwater treatment facilities) will also achieve pollutant load reductions in waters tributary to Lake Tahoe. The largest source of nitrogen in the Lake Tahoe (and Trout Creek) watershed is transportation-related emissions that lead to atmospheric nitrogen deposition. The Lake Tahoe TMDL also includes implementation measures to reduce atmospheric nitrogen sources. The Tahoe Regional Planning Agency leads efforts to improve transportation infrastructure and reduce overall vehicle miles traveled in the Lake Tahoe region to reduce emissions that lead to atmospheric nutrient loading. Public transit and vehicle fleet turnover are expected to further reduce nutrient-laden emissions in the Tahoe basin that will reduce nitrogen loading in the Trout Creek watershed. Furthermore, Federal, State, and larger local restoration agencies have well defined multi objective watershed restoration programs. These programs include maintenance activities (e.g., fuels reduction projects and restoring small disturbed sites) that are underway, or planned and expected, within the forested uplands of this watershed. Implementation of these measures will reduce or avoid increases in fine sediment and nutrient loads to Lake Tahoe and its tributaries including Trout Creek above Hwy 50. Finally, recent restoration efforts within this segment of Trout Creek completed by the City of South Lake Tahoe have restored geomorphic and hydrologic function and treatment of bankfull flows to help reduce nitrogen loading to this segment of Trout Creek. Pollutant load reductions within Trout Creek above Hwy 50 will be tracked through implementation of detailed performance and compliance measures and assessment and reporting protocols included in the Lake Tahoe TMDL. The TMDL Management System project is establishing activity-based tracking and reporting requirements to assess activities that are expected to reduce pollutant loading from non-urban sources. The Lahontan Water Board and the Nevada Division of Environmental Protection will implement a Lake Tahoe TMDL Management System for managing, tracking, integrating and evaluating new information generated from TMDL implementation actions, effectiveness monitoring, research efforts, and other factors such as climate change and wildfires. The Management System is based on an adaptive management framework to (1) link load reduction effectiveness with project implementation monitoring to improve project design and to assess if actual environmental improvement is occurring as expected; (2) establish guidance and operation protocols for how new information will be incorporated into project designs and TMDL program implementation; (3) establish prioritized TMDL research needs to fill data gaps and reduce uncertainties, and (4) implement a process for updating and reporting pollutant load reduction estimates and tracking projects within the TMDL implementation timeline. The Lake Tahoe TMDL requires implementation, effectiveness, and status and trends monitoring. Tributary stream status and trends monitoring will track long-term changes in water quality conditions relative to established water quality standards or goals, and project-specific monitoring will be used to assess the efficacy of various implementation measures. Long-term water quality trends and pollutant load reduction tracking in Trout Creek above Hwy 50 will be captured through the ongoing efforts of the Lake Tahoe Interagency Monitoring Program (LTIMP) whose primary objective is to monitor discharge, nutrient load, and sediment loads from representative streams that flow into Lake Tahoe. Nitrogen and phosphorus loading calculations are performed using the LTIMP flow and nutrient concentration database. LTIMP has monitored Trout Creek above Hwy 50 and other tributaries to Lake Tahoe since 1988; this data is stored on the USGS website at http://wdr.water.usgs.gov/.

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:	Pollutant load reductions within Trout Creek above Hwy 50 will be tracked through implementation of detailed performance and compliance measures and assessment and reporting protocols included in the Lake Tahoe TMDL. The TMDL Management System project is establishing activity-based tracking and reporting requirements to assess activities that are expected to reduce pollutant loading from non-urban sources. The Lahontan Water Board and the Nevada Division of Environmental Protection will implement a Lake Tahoe TMDL Management System for managing, tracking, integrating and evaluating new information generated from TMDL implementation actions, effectiveness monitoring, research efforts, and other factors such as climate change and wildfires. The Management System is based on an adaptive management framework to (1) link load reduction effectiveness with project implementation monitoring to improve project design and to assess if actual environmental improvement is occurring as expected; (2) establish guidance and operation protocols for how new information will be incorporated into project designs and TMDL program implementation; (3) establish prioritized TMDL research needs to fill data gaps and reduce uncertainties, and (4) implement a process for updating and reporting pollutant load reduction estimates and tracking projects within the TMDL implementation timeline. The Lake Tahoe TMDL requires implementation, effectiveness, and status and trends monitoring. Tributary stream status and trends monitoring will track long-term changes in water quality conditions relative to established water quality standards or goals, and project-specific monitoring will be used to assess the efficacy of various implementation measures. Long-term water quality trends and pollutant load reduction tracking in Trout Creek above Hwy 50 will be captured through the ongoing efforts of the Lake Tahoe Interagency Monitoring Program (LTIMP) whose primary objective is to monitor discharge, nutrient load, and sediment loads from representative streams that flow into Lake Tahoe. Nitrogen and phosphorus loading calculations are performed using the LTIMP flow and nutrient concentration database. LTIMP has monitored Trout Creek above Hwy 50 and other tributaries to Lake Tahoe since 1988; this data is stored on the USGS website at http://wdr.water.usgs.gov/.

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343122

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 1 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: Trout Creek at Saxon Creek Confluence (SLT-TROU-03)

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 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343121

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:

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 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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343139

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 Reference Condition Management Plan 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, 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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343095

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:
2 of 5 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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4644

Pollutant:

Nitrogen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 170489, Nitrogen	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343092

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: Trout Creek at Grinding Stone (SLT-TROU-02)

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


DECISION ID	163644	Region 6
Trout Creek (above Hwy 50)

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:	List on 303(d) list (being addressed by 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 SECTION of the Listing Policy. Under SECTION of the Policy, a minimum of one line of evidence is needed to assess listing status. Five 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. 11 of 11 samples exceeded the objective and these exceed the allowable frequency listed in Table 4.2 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 163644, Phosphorus	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4646

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:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 163644, Phosphorus	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343205

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 Reference Condition Management Plan 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 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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 163644, Phosphorus	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343218

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:
4 of 4 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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 163644, Phosphorus	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343231

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:
5 of 5 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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 163644, Phosphorus	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343234

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: Trout Creek at Saxon Creek Confluence (SLT-TROU-03)

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


DECISION ID	162043	Region 6
Trout Creek (above Hwy 50)

Pollutant:	Turbidity
Final Listing Decision:	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)(2018)
Revision Status	Revised
Sources:	Atmospheric Deposition \| Channel Erosion \| Urban Runoff--Erosion and Sedimentation
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 SECTION of the Listing Policy. Under SECTION of the Policy, a minimum of one line of evidence is needed to assess listing status. Thirteen 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. 30 of 114 samples exceeded the objective and these exceed the allowable frequency listed in Table 4.1 of the Listing Policy. 4. The Lake Tahoe Nutrient/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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340800

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 2 of 12 samples exceeded the water quality threshold for Turbidity.

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:

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: SLT-TROU-02 (Trout Creek at Grinding Stone).

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340866

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98966

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 16 of 54 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:

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 2 monitoring site(s) (USGS-10336780, USGS-10336790)

Temporal Representation:

The samples were collected between the dates of 2014-01-09 and 2016-09-15

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340958

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-TROU-09 (Trout Creek at Restoration Area).

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340828

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340868

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-TROU-11 (Trout Creek downstream of Pioneer Trail).

Temporal Representation:

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

Line of Evidence (LOE) for Decision ID 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340947

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 League to Save Lake Tahoe Truckee Tahoe Snapshot D data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 1 of 11 samples exceeded the water quality threshold for Turbidity.

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-TR15-02 (Trout Creek at Blackbart Bridge).

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340926

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 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340954

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-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340785

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 11 of 25 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field from the Section 319h Grants 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: 634TCUSGS (Trout Creek 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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97794

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 SWAMP Perennial Stream Surveys data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality standard for Turbidity.

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:

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98074

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 Reference Condition Management Plan (RCMP).

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(s) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162043, Turbidity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340964

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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	162044	Region 6
Trout Creek (above Hwy 50)

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. Seven lines of evidence are available in the administrative record to assess this pollutant. One of the 10 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. One of the 10 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 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

337835

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:

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:

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97316

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 TRPA Tahoe Ambient Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 1 of 4 samples exceeded the water quality standard for Alkalinity as CaCO3.

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:

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98268

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:

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 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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98725

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:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

337952

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

338008

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162044, Alkalinity as CaCO3	Region 6
Trout Creek (above Hwy 50)

LOE ID:

338025

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	101622	Region 6
Trout Creek (above Hwy 50)

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

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 101622, Ammonia	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98428

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:

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 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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 101622, Ammonia	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97918

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:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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	101621	Region 6
Trout Creek (above Hwy 50)

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. Two lines of evidence, one which assesses the available data against the COLD beneficial use and one which assesses the available data against the MUN beneficial use are available in the administrative record to assess this pollutant. 0 of 1 samples in each assessment 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 1 samples in each beneficial use assessment 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 per beneficial use assessment 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 101621, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98072

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 Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 101621, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98409

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

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:

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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	170486	Region 6
Trout Creek (above Hwy 50)

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 170486, Nitrogen, Nitrate	Region 6
Trout Creek (above Hwy 50)

LOE ID:

338943

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-TROU-02 (Trout Creek at Grinding Stone).

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 170486, Nitrogen, Nitrate	Region 6
Trout Creek (above Hwy 50)

LOE ID:

338937

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-TR15-02 (Trout Creek at Blackbart Bridge).

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 170486, Nitrogen, Nitrate	Region 6
Trout Creek (above Hwy 50)

LOE ID:

338953

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-TROU-07 (Trout Creek Behind College).

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


DECISION ID	170487	Region 6
Trout Creek (above Hwy 50)

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. Sixteen lines of evidence are available in the administrative record to assess this pollutant. Zero of the 44 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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 44 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340479

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:

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340537

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340438

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340635

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-TROU-09 (Trout Creek at Restoration Area).

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340416

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-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98077

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 SWAMP Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97312

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:

Water Board staff assessed TRPA Tahoe Ambient Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality standard for SpecificConductivity.

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97719

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 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:

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340413

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-TR15-02 (Trout Creek at Blackbart Bridge).

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340633

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340477

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340428

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340564

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-TROU-02 (Trout Creek at Grinding Stone).

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340655

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-TROU-04 (Trout Creek upstream of Saxon Creek Confluence).

Temporal Representation:

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

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340501

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 170487, Specific Conductivity	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340377

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-TROU-11 (Trout Creek downstream of Pioneer Trail).

Temporal Representation:

The samples were collected between the dates of 2002-05-04 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	162042	Region 6
Trout Creek (above Hwy 50)

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. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the 3samples 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. 0 of 3 samples exceeded the objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 162042, Sulfates	Region 6
Trout Creek (above Hwy 50)

LOE ID:

98318

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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 Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for Sulfate 250 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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 162042, Sulfates	Region 6
Trout Creek (above Hwy 50)

LOE ID:

97822

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for Sulfate 250 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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162042, Sulfates	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340720

Pollutant:

Sulfates

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for Sulfate 250 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	162041	Region 6
Trout Creek (above Hwy 50)

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339906

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 Trout Creek (above Hwy 50) 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:

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: SLT-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340030

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:

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-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340155

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:

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-TROU-04 (Trout Creek upstream of Saxon Creek Confluence).

Temporal Representation:

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

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339916

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 Trout Creek (above Hwy 50) 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:

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340043

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 Trout Creek (above Hwy 50) 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:

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340102

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 11 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-TR15-02 (Trout Creek at Blackbart Bridge).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340022

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 12 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-TROU-02 (Trout Creek at Grinding Stone).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339935

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 Trout Creek (above Hwy 50) 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:

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339739

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 11 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-TR15-02 (Trout Creek at Blackbart Bridge).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339689

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:

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340216

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:

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-TROU-09 (Trout Creek at Restoration Area).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339532

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339525

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339971

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Reference Condition Management Plan data for Trout Creek (above Hwy 50) 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 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339896

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340217

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:

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-TROU-09 (Trout Creek at Restoration Area).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339912

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:

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-TROU-04 (Trout Creek upstream of Saxon Creek Confluence).

Temporal Representation:

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

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340169

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340023

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 Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 0 of 12 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-TROU-02 (Trout Creek at Grinding Stone).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339652

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339809

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:

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340038

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 Trout Creek (above Hwy 50) 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:

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340113

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 Trout Creek (above Hwy 50) 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:

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

340201

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the Surface Water Ambient Monitoring Program for the 2026 Integrated Report in Region 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129814

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

0 of 0 samples exceeded the water quality standard for pH. Although pH data does exist for this waterbody, the objective for this pollutant requires background information that is currently unavailable, and therefore an assessment of water quality standards could not be made.

Data Reference:

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129751

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129722

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 Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129752

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the 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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129579

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162041, pH	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129572

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP 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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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	171778	Region 6
Trout Creek (above Hwy 50)

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. Eleven lines of evidence evaluating benthic-macroinvertebrate bioassessment data are available in the administrative record to assess this indicator. Three of fourteen 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, nitrogen, dissolved oxygen, and phosphorus). 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. 3 of 14 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 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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96676

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 collected data for the Surface Water Ambient Monitoring Program (SWAMP) Reference Condition Management Plan. A concentration of 0.2 mg/L was recorded, which exceeds the site specific objective.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for chloride in Trout Creek (above Hwy 50), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.15 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected from 634TRT001, which is located at the end of Fountain Place road upstream of the city of South Lake Tahoe.

Temporal Representation:

Data were collected on one occasion in August 2013.

Environmental Conditions:

Trout Creek drains the southern rim of the Lake Tahoe Basin, flowing from forested lands through the Bijou area of the city of South Lake Tahoe. The creek has been heavily impacted by urban development in its lower portions and has been the subject of several and ongoing restoration efforts.

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342758

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:
6 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 0.15 (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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342780

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:
2 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 0.15 (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: Trout Creek upstream of Martin Ave (SLT-TROU-08)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342764

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:
7 of 7 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 0.15 (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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4644

Pollutant:

Nitrogen

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

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

Data Reference:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343095

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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343092

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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343139

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:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for 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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343122

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: Trout Creek at Saxon Creek Confluence (SLT-TROU-03)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

130026

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:

Water Board staff assessed TRPA Tahoe Ambient Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 2 of 4 samples exceeded the water quality standard for Oxygen, Saturation.

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:

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343231

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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343205

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 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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343234

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: Trout Creek at Saxon Creek Confluence (SLT-TROU-03)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343218

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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4646

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:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

343121

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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339118

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:

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: SLT-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339073

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, 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339146

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339042

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-TR15-02 (Trout Creek at Blackbart Bridge).

Temporal Representation:

The samples were collected between the dates of 2009-05-16 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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339312

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-TROU-09 (Trout Creek at Restoration Area).

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339216

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

130002

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339434

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:

Water Board staff assessed TRPA Tahoe Ambient Monitoring data for Trout Creek (above Hwy 50) to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality threshold for Oxygen, Saturation.

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339231

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339230

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-TROU-11 (Trout Creek downstream of Pioneer Trail).

Temporal Representation:

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

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339133

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

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

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339248

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-TROU-04 (Trout Creek upstream of Saxon Creek Confluence).

Temporal Representation:

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

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339238

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339196

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-TROU-02 (Trout Creek at Grinding Stone).

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339039

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339492

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339394

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129975

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 Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129972

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96498

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 0.827410744 and 0.709550911. One of the two scores is not meeting the water quality objective.

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:

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:

Samples collected at the following stations:
634S15266
634S15290

Temporal Representation:

Sample collected on 9/15/2015 and 8/26/2015

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96438

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 1.139602, 1.023139, and 1.192296769. Therefore, this site is not exceeding the water quality objective for the aquatic life beneficial use. 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 Reference Condition Management Plan (RCMP).

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:

Samples collected at the following station: 634PS0062 and 634TRT001

Temporal Representation:

Samples Collected on 10/12/2011, 8/23/2001, and 8/26/2013.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Reference Condition Management Plan.

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96381

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 1.139601959. Therefore, this site is not exceeding the water quality objective for the aquatic life beneficial use.

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 634PS0062

Temporal Representation:

Collected on 10/12/2011

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

132778

Pollutant:

Habitat Assessment (Streams)

LOE Subgroup:

Ancillary Line of Evidence

Matrix:

-N/A

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

HABITAT ASSESSMENT

Data Used to Assess Water Quality:

The site had an IPI score of 1.05 and this score indicates that the habitat is likely intact at this site.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Physical characteristics of a site vary due to both natural factors and human disturbance. Statistical models based on a large statewide reference data set can help distinguish natural variability from anthropogenic stress. These models work across the diverse stream types found in California. The Index of Physical Habitat Integrity (IPI) is a multimetric Index developed based on these models to characterize physical habitat condition for streams in California. Index scores near 1 indicate physical habitat conditions similar to reference, whereas lower scores indicate degradation. For the purposes of making statewide assessments, three thresholds (analogous to those used for the CSCI) were established based on the 30th; 10th; and 1st percentiles of IPI scores at reference sites. These three thresholds divide the IPI scoring range into 4 categories of physical condition as follows: greater than or equal to 0.94 = likely intact condition; 0.93 to 0.84 = possibly altered condition; 0.83 to 0.71 = likely altered condition; less than or equal to 0.70 = very likely altered condition. Scores of 0.83 lower indicate that the physical habitat has been altered and low CSCI scores from this site may be due to impacts to the physical habitat.

Guideline Reference:

An Index to Measure the Quality of Physical Habitat in California Wadeable Streams

Spatial Representation:

Samples collected at the following station: 634TRT001

Temporal Representation:

Samples Collected on 8/26/2013.

Environmental Conditions:

QAPP Information:

QAPP for SWAMP Reference Condition Management Plan.

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352828

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 634S17322 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.806625 to 0.806625 .

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:

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

Samples were collected from 2017-10-10 to 2017-10-10.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352875

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 634TRT002 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.615906 to 0.615906 .

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: 634TRT002 (Trout Cr 4th Ord Lower).

Temporal Representation:

Samples were collected from 2016-08-25 to 2016-08-25.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352876

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 634TRT003 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.978119 to 0.978119 .

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

Samples were collected from 2017-09-08 to 2017-09-08.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352868

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 634TPB125 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.982211 to 0.982211 .

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

Samples were collected from 2017-09-12 to 2017-09-12.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352813

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 634S15290 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.716657 to 0.716657 .

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: 634S15290 (Trout Creek 634S15290).

Temporal Representation:

Samples were collected from 2015-08-26 to 2015-08-26.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352817

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 634S16293 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.007 to 1.007 .

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: 634S16293 (634S16293 Trout Creek).

Temporal Representation:

Samples were collected from 2016-09-29 to 2016-09-29.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352874

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 634TRCASC to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 1.097416439 to 1.097416439 .

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

Samples were collected from 2020-10-05 to 2020-10-05.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

352806

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 634S15266 to determine beneficial use support and the results are as follows: 0 of 1 samples exceeded the water quality standard. CSCI scores were from 0.813468 to 0.813468 .

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: 634S15266 (634S15266 Trout Creek Status 2015).

Temporal Representation:

Samples were collected from 2015-09-15 to 2015-09-15.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342791

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 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 0.15 (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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342774

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 0.15 (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: Trout Creek Behind College (SLT-TROU-07)

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 171778, Benthic Community Effects	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96675

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 collected data for the Surface Water Ambient Monitoring Program (SWAMP) Perennial Stream Survey project. A concentration of 0.3 mg/L was recorded, which exceeds the site specific objective.

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 site specific objective for chloride in Trout Creek (above Hwy 50), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.15 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected from 634PS0062, which is located approx. 0.25 miles up-gradient of Pioneer Trail near the confluence with Saxon Creek in South of Lake Tahoe.

Temporal Representation:

Data were collected on one occasion in October 2011.

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	163643	Region 6
Trout Creek (above Hwy 50)

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. Seven lines of evidence are available in the administrative record to assess this pollutant. Nineteen of the 19 samples exceed the water quality 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. Nineteen of the 19 samples exceed the water quality 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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96676

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:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the SWAMP Reference Condition Management Plan (RCMP).

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site specific objective for chloride in Trout Creek (above Hwy 50), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.15 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected from 634TRT001, which is located at the end of Fountain Place road upstream of the city of South Lake Tahoe.

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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342791

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 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 0.15 (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: Trout Creek ~0.4mi above Saxon Creek (634TRCASC)

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342758

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 0.15 (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: Trout Creek at Grinding Stone (SLT-TROU-02)

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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342774

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 0.15 (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: Trout Creek Behind College (SLT-TROU-07)

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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342780

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 0.15 (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: Trout Creek upstream of Martin Ave (SLT-TROU-08)

Temporal Representation:

The samples were collected between the dates of 2014-05-17 and 2015-05-16

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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

342764

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 0.15 (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: Trout Creek at Blackbart Bridge (SLT-TR15-02)

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 163643, Chloride	Region 6
Trout Creek (above Hwy 50)

LOE ID:

96675

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:

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 site specific objective for chloride in Trout Creek (above Hwy 50), as referenced in the Lahontan Basin Plan table 3-12, is an annual average concentration not to exceed 0.15 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data were collected from 634PS0062, which is located approx. 0.25 miles up-gradient of Pioneer Trail near the confluence with Saxon Creek in South of Lake Tahoe.

Temporal Representation:

Data were collected on one occasion in October 2011.

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	162040	Region 6
Trout Creek (above Hwy 50)

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. Twenty lines of evidence are available in the administrative record to assess this parameter: 16 which assess dissolved oxygen concentration data and 4 which assess dissolved oxygen percent saturation data. Zero of 42 samples are below the objective for minimum dissolved oxygen concentration. Five of 7 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. Five of 7 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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339133

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-TROU-08 (Trout Creek upstream of Martin Ave).

Temporal Representation:

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

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339118

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-TROU-03 (Trout Creek at Saxon Creek Confluence).

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339248

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-TROU-04 (Trout Creek upstream of Saxon Creek Confluence).

Temporal Representation:

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

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339238

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-TROU-07 (Trout Creek Behind College).

Temporal Representation:

The samples were collected between the dates of 2001-06-02 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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339231

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339230

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-TROU-11 (Trout Creek downstream of Pioneer Trail).

Temporal Representation:

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

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339312

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-TROU-09 (Trout Creek at Restoration Area).

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339146

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339039

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-TROU-10 (Trout Creek upstream of Pioneer Trail).

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

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339042

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-TR15-02 (Trout Creek at Blackbart Bridge).

Temporal Representation:

The samples were collected between the dates of 2009-05-16 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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339196

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-TROU-02 (Trout Creek at Grinding Stone).

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339394

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: 634TPB125 (Trout Creek 634010125 Trend Panel B).

Temporal Representation:

The samples were collected between the dates of 2017-09-12 and 2017-09-12

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339216

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339434

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: 634S17322 (634S17322 Trout Creek Status 2017).

Temporal Representation:

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

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129972

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) (634PS0062)

Temporal Representation:

The samples were collected between the dates of 2011-10-12 and 2011-10-12

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

129975

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 Reference Condition Management Plan (RCMP).

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) (634TRT001)

Temporal Representation:

The samples were collected between the dates of 2013-08-26 and 2013-08-26

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

130002

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

130026

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:

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 4 monitoring site(s) (634S15266, 634S15290, 634S16293, 634TRT002)

Temporal Representation:

The samples were collected between the dates of 2015-08-26 and 2016-09-29

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 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339073

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, 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: 634TRCASC (Trout Creek ~0.4mi above Saxon Creek).

Temporal Representation:

The samples were collected between the dates of 2020-10-05 and 2020-10-05

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 162040, Oxygen, Dissolved	Region 6
Trout Creek (above Hwy 50)

LOE ID:

339492

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: 634TRT003 (Trout Cr 4th Ord Upper).

Temporal Representation:

The samples were collected between the dates of 2017-09-08 and 2017-09-08

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP


DECISION ID	69220	Region 6
Trout Creek (above Hwy 50)

Pollutant:	Iron
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed. The TMDL completion date has been updated to 2031.

Regional Board Decision Recommendation:	This region was not assessed this cycle. All decisions have been carried over from the previous cycle and remain the same.

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 69220, Iron	Region 6
Trout Creek (above Hwy 50)

LOE ID:

4643

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:

Placeholder reference pre-2006 303(d)

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Unspecified

Objective/Criterion Reference:

Placeholder reference pre-2006 303(d)

Evaluation Guideline:

Unspecified

Guideline Reference:

Placeholder reference pre-2006 303(d)

Spatial Representation:

Unspecified

Temporal Representation:

Unspecified

Environmental Conditions:

Unspecified

QAPP Information:

Unspecified

QAPP Information Reference(s):