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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Hidden Valley Creek
Water Body ID:	CAR6341002020011213121317
Water Body Type:	River & Stream


DECISION ID	168992	Region 6
Hidden Valley Creek

Pollutant:	Phosphorus
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	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 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 line of evidence is available in the administrative record to assess this pollutant. 15 of 15 samples exceed the water quality objective for COLD. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for placing this water segment-pollutant combination on the 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. 15 of the 15 samples exceeded the objective and 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 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 168992, Phosphorus	Region 6
Hidden Valley Creek

LOE ID:

31898

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:

Two of the two annual averages exceeded the water quality objective for total phosphorus. Annual averages were calculated by water year starting in October 1st through September 30th. A total of 28 samples were collected.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Table 5.1-3 of the Basin Plan states that the water quality objective for total phosphorus for Trout Creek is an annual average objective of 0.015 mg/L. Hidden Valley Creek is a tributary of Trout Creek.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected from 10/23/2007 to 9/15/2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 168992, Phosphorus	Region 6
Hidden Valley Creek

LOE ID:

347853

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
13 of 13 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557


DECISION ID	103229	Region 6
Hidden Valley Creek

Pollutant:	Alkalinity as CaCO3
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 that each consist of a single sample. One of two samples exceed the guideline for alkalinity. 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 two samples exceeded 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. 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 103229, Alkalinity as CaCO3	Region 6
Hidden Valley Creek

LOE ID:

97337

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 Hidden Valley Creek to determine beneficial use support and results are as follows: 1 of 1 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 1 monitoring site(s) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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 103229, Alkalinity as CaCO3	Region 6
Hidden Valley Creek

LOE ID:

97842

Pollutant:

Alkalinity as CaCO3

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Reference Condition Management Plan data for Hidden Valley Creek to determine beneficial use support and results are as follows: 0 of 1 samples exceeded the water quality standard for Alkalinity as CaCO3.

Data Reference:

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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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	103232	Region 6
Hidden Valley Creek

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. One line of evidence is available in the administrative record to assess this pollutant. Zero of one samples exceed the criteria for ammonia. 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 one samples exceeded the criteria 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. 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 103232, Ammonia	Region 6
Hidden Valley Creek

LOE ID:

97880

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:

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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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	162027	Region 6
Hidden 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:	Pollution

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 33 samples exceed the guideline for nitrate/nitrite as N. 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 233 samples exceeded the guideline 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 162027, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Hidden Valley Creek

LOE ID:

338836

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

206

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed HeavenlyValley_TMDL data for Hidden Valley Creek to determine beneficial use support and results are as follows: 0 of 206 samples exceeded the water quality threshold for Nitrate + Nitrite as N.

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: HDVC-5 (Hidden Valley Creek - Reference Station).

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 162027, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Hidden Valley Creek

LOE ID:

98731

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 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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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 162027, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Hidden Valley Creek

LOE ID:

31889

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:

None of the 26 samples exceeded the water quality objective for nitrate + nitrate as N. Samples collected within a 7-day period were averaged and considered as a single sample.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan, Lahontan Basin, Objective for Municipal and Domestic Supply uses of inland surface waters states the following: waters shall not contain concentrations of inorganic chemicals in excess of the limits specified in California Code of Regulations, Title 22, Table 64431-A of section 64431 (Inorganic Chemicals). The maximum contaminant level listed in Table 64431-A for nitrate + nitrite as N is 10.0 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected from 10/23/2007 to 9/15/2009.

Environmental Conditions:

A storm event occurred during the sampling on 3/2/2009.

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):


DECISION ID	103230	Region 6
Hidden 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:	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. Three lines of evidence are available in the administrative record to assess this pollutant. Zero of two samples exceed the objective for dissolved oxygen concentration and one of one samples exceed the objective for 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. Zero of two samples exceed the objective for dissolved oxygen concentration and one of one samples exceed the objective for saturation 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. 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 103230, Oxygen, Dissolved	Region 6
Hidden Valley Creek

LOE ID:

130131

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:

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(s) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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 103230, Oxygen, Dissolved	Region 6
Hidden Valley Creek

LOE ID:

130001

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 1 monitoring site(s) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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 103230, Oxygen, Dissolved	Region 6
Hidden Valley Creek

LOE ID:

130116

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 Hidden Valley Creek to determine beneficial use support and results are as follows: 0 of 1 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 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 1 monitoring site(s) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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	103231	Region 6
Hidden 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:	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 that each consist of a single sample. Zero of two samples exceed the guideline for specific conductivity. 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 two samples exceeded 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. 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 103231, Specific Conductivity	Region 6
Hidden Valley Creek

LOE ID:

97361

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

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

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

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) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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 103231, Specific Conductivity	Region 6
Hidden Valley Creek

LOE ID:

98097

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:

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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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	162028	Region 6
Hidden Valley Creek

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

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. Twelve of 222 samples exceed the guideline for turbidity. 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. 12 of 222 samples exceeded 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 162028, Turbidity	Region 6
Hidden Valley Creek

LOE ID:

340952

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

206

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed HeavenlyValley_TMDL data for Hidden Valley Creek to determine beneficial use support and results are as follows: 11 of 206 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: HDVC-5 (Hidden Valley Creek - Reference Station).

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 162028, Turbidity	Region 6
Hidden Valley Creek

LOE ID:

97906

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:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Lahontan Basin Plan's \Chemical Constituents\" objective. The Secondary MCL for turbidity is 5 NTU. Calculation of a numeric objective for other beneficial uses requires comparison with upstream or other background data which may not be available as part of the data used for water quality assessment. "

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site(s) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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 162028, Turbidity	Region 6
Hidden Valley Creek

LOE ID:

32457

Pollutant:

Turbidity

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:

One of the fifteen turbidity samples exceeded the MCL in this water body.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the following sampling stie: HV-H5 (Hidden Creek)

Temporal Representation:

Samples were collected monthly between August of 2008 and September of 2009.

Environmental Conditions:

QAPP Information:

Data were collected for NPDES permit R6T-2003-0032. This data was collected under waste discharge requirements for a TMDL and therefore is of adequate quality.

QAPP Information Reference(s):


DECISION ID	103825	Region 6
Hidden Valley Creek

Pollutant:	pH
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. Four lines of evidence are available in the administrative record to assess this pollutant, two that assess for COLD and two for MUN.The Basin Plan pH objective requires background data that is unavailable, consequently the pH data cannot be assessed. All the lines of evidence show zero of zero 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. [NUMBER] of [NUMBER] samples exceeded the [OBJECTIVE/GUIDELINE/CRITERIA] 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. 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 103825, pH	Region 6
Hidden Valley Creek

LOE ID:

129671

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 Reference Condition Management Plan (RCMP).

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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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 103825, pH	Region 6
Hidden Valley Creek

LOE ID:

129769

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 1 monitoring site(s) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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 103825, pH	Region 6
Hidden Valley Creek

LOE ID:

129611

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 1 monitoring site(s) (634S16313)

Temporal Representation:

The samples were collected between the dates of 2016-07-06 and 2016-07-06

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 103825, pH	Region 6
Hidden Valley Creek

LOE ID:

129636

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) (634HID001)

Temporal Representation:

The samples were collected between the dates of 2011-10-03 and 2011-10-03

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	171833	Region 6
Hidden Valley Creek

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. 16 line(s) of evidence evaluating benthic-macroinvertebrate bioassessment data is/are available in the administrative record to assess this indicator. 5 of 13 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, Iron, Phosphorus, Total Nitrogen as N). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for placing Benthic Community Effects in this waterbody segment on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. 5 of 13 benthic-macroinvertebrate bioassessment samples had CSCI scores below 0.79. Therefore, this water body is exceeding the water quality threshold for the protection of the WARM and/or COLD beneficial use. 4. Pursuant to section 3.9 of the Listing Policy, the water segment has associated pollutant(s) samples that exceed water quality objectives. 5. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

347737

Pollutant:

Iron

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
2 of 2 samples exceeded the water quality threshold for Iron

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Iron in this water body is 0.03 (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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2011-06-22

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

32440

Pollutant:

Chloride

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:

The annual averages from the sampling location in 2008 and 2009 this water body exceeded the water quality objective. One measurement was used to calculate the annual average for 2008 and 3 samples were used to calculate the annual average in 2009.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective is an annual average of 0.15 mg/L. (from Table 5.1-3 of the Lahontan Region Basin Plan).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the following sampling stie: HV-H5 (Hidden Creek)

Temporal Representation:

Samples were collected once quarterly between August of 2008 and September of 2009.

Environmental Conditions:

QAPP Information:

Data were collected for NPDES permit R6T-2003-0032. This data was collected under waste discharge requirements for a TMDL and therefore is of adequate quality.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

31978

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The annual average is 0.18 mg/L which is above the objective of 0.03 mg/L.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Table 3-12 of the Basin Plan, states the annual average for iron in the Trout Creek watershed (Figure 3-6) is 0.03 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected quarterly from the fourth quarter of 2008 to the third quarter of 2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

347853

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
13 of 13 samples exceeded the water quality threshold for Phosphorus as P

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

31898

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:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

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:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected from 10/23/2007 to 9/15/2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

347769

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
2 of 13 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

31888

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:

None of the two annual averages exceeded the water quality objective for total nitrogen. Annual averages were calculated by water year starting in October 1st through September 30th. A total of 28 samples were collected per site.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Table 5.1-3 of the Basin Plan states that the water quality objective for total nitrogen for Trout Creek is an annual average objective of 0.19 mg/L. Hidden Valley Creek is a tributary of Trout Creek.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected from 10/23/2007 to 9/15/2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

352878

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 634UHC-1 to determine beneficial use support and the results are as follows: 2 of 2 samples exceeded the water quality standard. CSCI scores were from 0.72 to 0.78 .

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

The California Stream Condition Index (CSCI) is a biological scoring tool that helps aquatic resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score is calculated by comparing the expected condition with actual (observed) results (Rhen, A.C. et al., 2015). CSCI scores range from 0 (highly degraded) to greater than 1 (equivalent to reference). CSCI scoring of biological condition are as follows (per the scientific paper supporting the development of the CSCI scoring tool): greater than or equal to 0.92 = likely intact condition, 0.91 to 0.80 = possibly altered condition, 0.79 to 0.63 = likely altered condition, less than or equal to 0.62 = very likely altered condition. Sites with scores below 0.79 are considered to have exceeded the water quality objective for the aquatic life beneficial use.)

Guideline Reference:

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

Spatial Representation:

The samples were collected at 1 monitoring site: 634UHC-1 (Hidden Valley Creek, Upper).

Temporal Representation:

Samples were collected from 2018-07-10 to 2019-07-24.

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

352825

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 634S16313 to determine beneficial use support and the results are as follows: 1 of 1 samples exceeded the water quality standard. CSCI scores were from 0.626904 to 0.626904 .

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: 634S16313 (634S16313 Hidden Valley Creek Status 2016).

Temporal Representation:

Samples were collected from 2016-07-06 to 2016-07-06.

Environmental Conditions:

QAPP Information:

Generic SWAMP QAPrP

QAPP Information Reference(s):

Generic SWAMP QAPrP

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

347711

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
11 of 11 samples exceeded the water quality threshold for Chloride

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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 0.2 (mg/L), (as a 90th Percentile).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2011-02-22 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

96913

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP Reference Condition Management Plan data for Hidden Valley Creek to determine beneficial use support and results are as follows: 1 of 1 samples exceeded the water quality standard for Chloride. The single sample was 0.31 mg/L.

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 Lahontan Basin Plan objective for Trout Creek (table 3-12) for chloride is 0.15 mg/L annual average. This objective is applied as per the tributary rule as stated in Chapter 2 of the Basin Plan: " additional beneficial uses may apply to waters with in these categories under the "tributary rule", which provides that water quality standards for specific waterbodies apply upstream to tributaries for which no site-specific standards have been adopted."

Objective/Criterion Reference:

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) (634HID001)

Temporal Representation:

The sample was collected 2011-10-03

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

347667

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
12 of 13 samples exceeded the water quality threshold for Chloride

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

132772

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 0.97 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:

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:

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: 634HID001

Temporal Representation:

Samples Collected on 10/3/2011.

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 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

96426

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 1.077372, 1.166088, 1.175474651. 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: 634HID001

Temporal Representation:

Samples Collected on 7/30/2001, 7/3/2002, and 10/3/2011.

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 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

96458

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:

There were six CSCI scores from this water body. The scores were:
0.923217014
0.901331525
0.880172031
0.728185618
0.58016013

Two of the five scores were exceeding the water quality objective for the aquatic life beneficial use. It should be noted that the two exceeding scores were from station 634UHC-1

Data Reference:

Water Quality Assessment Data for the 2018 solicitation cycle submitted through CEDEN for Heavenly Valley TMDL.

SWAMP Data:

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 were collected at station 634LHC-1 and 634UHC-1

Temporal Representation:

Samples were collected at each location on the following dates:
6/11/2015
8/29/2011
7/29/2014
7/22/2016
6/8/2015

Environmental Conditions:

QAPP Information:

QAPP for Heavenly Valley TMDL

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 171833, Benthic Community Effects	Region 6
Hidden Valley Creek

LOE ID:

352783

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 634LHC-1 to determine beneficial use support and the results are as follows: 0 of 2 samples exceeded the water quality standard. CSCI scores were from 1.14 to 1.16 .

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: 634LHC-1 (Hidden Valley Creek, Lower).

Temporal Representation:

Samples were collected from 2018-07-11 to 2019-07-25.

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557


DECISION ID	162025	Region 6
Hidden Valley Creek

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. Four lines of evidence are available in the administrative record to assess this pollutant. 26 of the 27 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. 26 of 27 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 162025, Chloride	Region 6
Hidden Valley Creek

LOE ID:

347667

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
12 of 13 samples exceeded the water quality threshold for Chloride

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 162025, Chloride	Region 6
Hidden Valley Creek

LOE ID:

347711

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
11 of 11 samples exceeded the water quality threshold for Chloride

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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 0.2 (mg/L), (as a 90th Percentile).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2011-02-22 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 162025, Chloride	Region 6
Hidden Valley Creek

LOE ID:

32440

Pollutant:

Chloride

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:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The water quality objective is an annual average of 0.15 mg/L. (from Table 5.1-3 of the Lahontan Region Basin Plan).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at the following sampling stie: HV-H5 (Hidden Creek)

Temporal Representation:

Samples were collected once quarterly between August of 2008 and September of 2009.

Environmental Conditions:

QAPP Information:

Data were collected for NPDES permit R6T-2003-0032. This data was collected under waste discharge requirements for a TMDL and therefore is of adequate quality.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 162025, Chloride	Region 6
Hidden Valley Creek

LOE ID:

96913

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:

Objective/Criterion Reference:

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) (634HID001)

Temporal Representation:

The sample was collected 2011-10-03

Environmental Conditions:

QAPP Information:

Quality Assurance Program Plan and Standard Operating Procedures for SWAMP program

QAPP Information Reference(s):


DECISION ID	162026	Region 6
Hidden Valley Creek

Pollutant:	Iron
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Three lines of evidence, one to evaluate MUN and two to evaluate COLD, are available in the administrative record to assess this pollutant. One out of four samples exceeded the MCL for protection of MUN and three of three samples exceeded the objective for protection of COLD. 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. Three of three samples exceeded the objective for protection of COLD, 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 162026, Iron	Region 6
Hidden Valley Creek

LOE ID:

347737

Pollutant:

Iron

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
2 of 2 samples exceeded the water quality threshold for Iron

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load for the 2026 Integrated Report in Region 6

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Basin Plan objective for Iron in this water body is 0.03 (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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-10-20 and 2011-06-22

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557

Line of Evidence (LOE) for Decision ID 162026, Iron	Region 6
Hidden Valley Creek

LOE ID:

31978

Pollutant:

Iron

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The annual average is 0.18 mg/L which is above the objective of 0.03 mg/L.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Table 3-12 of the Basin Plan, states the annual average for iron in the Trout Creek watershed (Figure 3-6) is 0.03 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected quarterly from the fourth quarter of 2008 to the third quarter of 2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 162026, Iron	Region 6
Hidden Valley Creek

LOE ID:

31977

Pollutant:

Iron

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:

One of the four samples exceeded the secondary MCL.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan, Lahontan Basin, Objective for Municipal and Domestic Supply uses of inland surface waters states the following: waters shall not contain concentrations of inorganic chemicals in excess of the limits specified in California Code of Regulations, Title 22,Table 64449-B of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The secondary MCL for iron is 0.3 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected quarterly from the fourth quarter of 2008 to the third quarter of 2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):


DECISION ID	169954	Region 6
Hidden Valley Creek

Pollutant:	Nitrogen
Final Listing Decision:	List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2018)
Revision Status	Revised
Sources:	A Source Unknown
TMDL Priority:	Low
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Two of the 15 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. Two of 15 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 169954, Nitrogen	Region 6
Hidden Valley Creek

LOE ID:

31888

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:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

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:

Samples were collected at HV-H5 Hidden Valley Creek baseline station.

Temporal Representation:

Samples were collected from 10/23/2007 to 9/15/2009.

Environmental Conditions:

QAPP Information:

Data were collected as part of Water Discharge Requirements R6T-2003-0032 for Heavenly Mountain Resort.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 169954, Nitrogen	Region 6
Hidden Valley Creek

LOE ID:

347769

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 HeavenlyValley_TMDL data to determine beneficial use support and results are as follows:
2 of 13 samples exceeded the water quality threshold for Nitrogen, Total

Data Reference:

Benthic, Field, Habitat, WQ from the Total Maximum Daily Load 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: Hidden Valley Creek - Reference Station (HDVC-5)

Temporal Representation:

The samples were collected between the dates of 2010-09-27 and 2022-09-21

Environmental Conditions:

QAPP Information:

Heavenly Resort QAPP

QAPP Information Reference(s):

Lahontan Water Board - HeavenlyResortQAPP - HeavenlyValley_TMDL - 402557


DECISION ID	79424	Region 6
Hidden Valley Creek

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2016)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for placement on the 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. One line of evidence is available in the administrative record to assess this pollutant. None of the 15 samples exceeds 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 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. None of the 15 samples exceed the objective but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of 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:	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 79424, Temperature, water	Region 6
Hidden Valley Creek

LOE ID:

31954

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

None of the 15 samples exceeded the evaluation guideline for temperature in this water body.

Data Reference:

Data from discharger self-monitoring reports for the Heavenly Mountain Resort ski area at Lake Tahoe, Oct. 2007-Sep. 2009

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses.(Water Quality Control Plan for the Lahontan Region)

Objective/Criterion Reference:

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

Evaluation Guideline:

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

Guideline Reference:

Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis

Spatial Representation:

Samples were collected at site HV-H5 (Hidden Creek).

Temporal Representation:

Samples were collected monthly between October of 2008 and September of 2009.

Environmental Conditions:

QAPP Information:

This data was collected under waste discharge requirements for a TMDL and therefore is of adequate quality.

QAPP Information Reference(s):