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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Union Valley Creek
Water Body ID:	CAR6352005020171102045945
Water Body Type:	River & Stream


DECISION ID	170327	Region 6
Union Valley Creek

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. 0 of 18 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 0 of 18 samples exceeded the objective and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples are needed to determine if a beneficial use is fully supported using table 3.1. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list 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 170327, Ammonia	Region 6
Union Valley Creek

LOE ID:

338313

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Ammonia as N, Unionized.

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: MTRGLEN02 (Union Valley Creek above Glenshire Road).

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2019-09-19

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 170327, Ammonia	Region 6
Union Valley Creek

LOE ID:

97410

Pollutant:

Nitrogen, ammonia (Total Ammonia)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Truckee River Watershed Council.

SWAMP Data:

Non-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 2 monitoring site(s) (MTRGLEN00, MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2016-09-23

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 170327, Ammonia	Region 6
Union Valley Creek

LOE ID:

338299

Pollutant:

Ammonia (Unionized)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 4 samples exceeded the water quality threshold for Ammonia as N, Unionized.

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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: MTRGLEN00 (Union Valley Creek at SFFCC road).

Temporal Representation:

The samples were collected between the dates of 2018-05-19 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	101488	Region 6
Union Valley Creek

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant, one for the geometric mean calculation and one for the statistical threshold value assessment. Both lines of evidence use the same data and so the sample sizes should not be added in this case. 3 of 9 samples in each beneficial use 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. 3 of 9 samples in each of the line of evidence exceeded the objectives and these sample sizes are insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 26 samples are needed to determine if a beneficial use is fully supported using table 3.2. 4. Pursuant to SECTION 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 101488, Indicator Bacteria	Region 6
Union Valley Creek

LOE ID:

129437

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the water quality standard for Coliform, Fecal. The water quality standard is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Truckee River Watershed Council.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 2 monitoring site(s), station(s): MTRGLEN00, MTRGLEN02

Temporal Representation:

The samples were collected between the days of 2011-05-14 and 2016-05-14 .

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 101488, Indicator Bacteria	Region 6
Union Valley Creek

LOE ID:

129440

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and the results are as follows: 3 of the 9 samples exceeded the logmean water quality standard for Coliform, Fecal. This is a 30-day rolling logmean that is calculated daily.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Truckee River Watershed Council.

SWAMP 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 2 monitoring site(s), station(s): MTRGLEN00, MTRGLEN02

Temporal Representation:

The samples were collected between the days of 2011-05-14 and 2016-05-14 .

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	162680	Region 6
Union Valley Creek

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:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of the 24 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 in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of the 24 samples exceed the objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 162680, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Union Valley Creek

LOE ID:

338825

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Nitrate + Nitrite as N.

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-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: MTRGLEN02 (Union Valley Creek above Glenshire Road).

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162680, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Union Valley Creek

LOE ID:

98649

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 12 samples exceeded the water quality standard for Nitrate + Nitrite as N.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Truckee River Watershed Council.

SWAMP 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 2 monitoring site(s) (MTRGLEN00, MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2011-05-14 and 2016-09-23

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162680, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Union Valley Creek

LOE ID:

338832

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 7 samples exceeded the water quality threshold for Nitrate + Nitrite as N.

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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: MTRGLEN00 (Union Valley Creek at SFFCC road).

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	163816	Region 6
Union Valley Creek

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Five lines of evidence are available in the administrative record to assess this parameter: 3 which assess dissolved oxygen concentration data and 2 which assess dissolved oxygen percent saturation data. Four of 54 samples are below the objective for minimum dissolved oxygen concentration. Three of 22 samples are below the objective for minimum dissolved oxygen percent saturation. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four of 54 samples are below the objective for minimum dissolved oxygen concentration. Three of 22 samples are below the objective for minimum dissolved oxygen percent saturation. This does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163816, Oxygen, Dissolved	Region 6
Union Valley Creek

LOE ID:

351211

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
1 of 12 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek at SFFCC road (MTRGLEN00)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 163816, Oxygen, Dissolved	Region 6
Union Valley Creek

LOE ID:

351255

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
2 of 10 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 80 (%), (as a Min).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek above Glenshire Road (MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 163816, Oxygen, Dissolved	Region 6
Union Valley Creek

LOE ID:

129961

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 Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 1 of 26 samples exceeded the water quality standard for Oxygen, Dissolved.

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for the Truckee River Watershed Council.

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 2 monitoring site(s) (MTRGLEN00, MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2010-09-23 and 2016-09-23

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 163816, Oxygen, Dissolved	Region 6
Union Valley Creek

LOE ID:

351322

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
2 of 14 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek at SFFCC road (MTRGLEN00)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 163816, Oxygen, Dissolved	Region 6
Union Valley Creek

LOE ID:

351374

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
1 of 14 samples fell below the minimum water quality threshold for Oxygen, Dissolved

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Oxygen, Dissolved in this water body is 7 (mg/L), (as a Min).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek above Glenshire Road (MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	170328	Region 6
Union Valley Creek

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

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

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list 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 170328, Specific Conductivity	Region 6
Union Valley Creek

LOE ID:

340580

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data for Union Valley Creek to determine beneficial use support and results are as follows: 0 of 8 samples exceeded the water quality threshold for SpecificConductivity.

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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 (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: MTRGLEN02 (Union Valley Creek above Glenshire Road).

Temporal Representation:

The samples were collected between the dates of 2019-05-18 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 170328, Specific Conductivity	Region 6
Union Valley Creek

LOE ID:

340576

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 Truckee River Watershed Council 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: MTRGLEN00 (Union Valley Creek at SFFCC road).

Temporal Representation:

The samples were collected between the dates of 2017-06-23 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	162681	Region 6
Union Valley Creek

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 162681, pH	Region 6
Union Valley Creek

LOE ID:

340151

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 Truckee River Watershed Council data for Union Valley Creek 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:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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: MTRGLEN02 (Union Valley Creek above Glenshire Road).

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162681, pH	Region 6
Union Valley Creek

LOE ID:

340118

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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: MTRGLEN00 (Union Valley Creek at SFFCC road).

Temporal Representation:

The samples were collected between the dates of 2018-05-19 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162681, pH	Region 6
Union Valley Creek

LOE ID:

339756

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 Truckee River Watershed Council 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: MTRGLEN02 (Union Valley Creek above Glenshire Road).

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162681, pH	Region 6
Union Valley Creek

LOE ID:

129738

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 Truckee River Watershed Council.

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 2 monitoring site(s) (MTRGLEN00, MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2010-09-23 and 2016-09-23

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162681, pH	Region 6
Union Valley Creek

LOE ID:

129737

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 Truckee River Watershed Council.

SWAMP 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 2 monitoring site(s) (MTRGLEN00, MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2010-09-23 and 2016-09-23

Environmental Conditions:

QAPP Information:

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 162681, pH	Region 6
Union Valley Creek

LOE ID:

340183

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 Truckee River Watershed Council 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: MTRGLEN00 (Union Valley Creek at SFFCC road).

Temporal Representation:

The samples were collected between the dates of 2018-05-19 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	169009	Region 6
Union Valley Creek

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 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. Eight of the 8 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eight of 8 samples exceed the objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 169009, Phosphorus	Region 6
Union Valley Creek

LOE ID:

347921

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council 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:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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 0.05 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek at SFFCC road (MTRGLEN00)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 169009, Phosphorus	Region 6
Union Valley Creek

LOE ID:

347927

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council 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:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council 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 0.05 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek above Glenshire Road (MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	170329	Region 6
Union Valley Creek

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 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. Six of the 8 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Six of 8 samples exceed the objective and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 170329, Total Kjeldahl Nitrogen (TKN)	Region 6
Union Valley Creek

LOE ID:

348008

Pollutant:

Total Kjeldahl Nitrogen (TKN)

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 Truckee River Watershed Council data to determine beneficial use support and results are as follows:
3 of 4 samples exceeded the water quality threshold for Nitrogen, Total Kjeldahl

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total Kjeldahl in this water body is 0.26 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek at SFFCC road (MTRGLEN00)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 170329, Total Kjeldahl Nitrogen (TKN)	Region 6
Union Valley Creek

LOE ID:

348025

Pollutant:

Total Kjeldahl Nitrogen (TKN)

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 Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Nitrogen, Total Kjeldahl in this water body is 0.26 (mg/L), (as a MOMMPR).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek above Glenshire Road (MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.


DECISION ID	163817	Region 6
Union Valley Creek

Pollutant:	Turbidity
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. Two lines of evidence are available in the administrative record to assess this pollutant. Seven of the 8 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Seven of the 8 samples exceed the objective, and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 163817, Turbidity	Region 6
Union Valley Creek

LOE ID:

343446

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
4 of 4 samples exceeded the water quality threshold for Turbidity

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 3 (NTU), (as a MOMM).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek above Glenshire Road (MTRGLEN02)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.

Line of Evidence (LOE) for Decision ID 163817, Turbidity	Region 6
Union Valley Creek

LOE ID:

343471

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Truckee River Watershed Council data to determine beneficial use support and results are as follows:
3 of 4 samples exceeded the water quality threshold for Turbidity

Data Reference:

Benthic, Field, Habitat, WQ from the Truckee River Watershed Council for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Turbidity in this water body is 3 (NTU), (as a MOMM).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Union Valley Creek at SFFCC road (MTRGLEN00)

Temporal Representation:

The samples were collected between the dates of 2017-05-20 and 2020-10-02

Environmental Conditions:

QAPP Information:

QAPP for Truckee River Monitoring Plan

QAPP Information Reference(s):

Quality Assurance Project Plan (QAPP) for Truckee River Monitoring Plan.