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

Supporting Information

Regional Board 1 - North Coast Region

Water Body Name:	Winchuck River HU, Gilbert Creek
Water Body ID:	CAR1010000020180427050633
Water Body Type:	River & Stream


DECISION ID	158665	Region 1
Winchuck River HU, Gilbert 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. Four lines of evidence are available in the administrative record to assess this pollutant. For the COLD FRESHWATER HABITAT beneficial use, there are two lines of evidence and 0 of the 731 samples exceed the objective. For the FISH SPAWNING beneficial use, there are two lines of evidence and 0 of the 731 samples exceed the objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 731 samples exceeded the criteria for both the COLD and SPWN beneficial uses 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 158665, Oxygen, Dissolved	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328871

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Fish Spawning

Number of Samples:

463

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 463 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Dissolved oxygen concentrations shall conform to those limits listed in Section 3.3.5. Section 3.3.5 lists dissolved oxygen concentration limits for SPAWN beneficial use waters to be a daily minimum of 9.0 mg/L and a 7-day moving average of 11.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2013-02-13 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158665, Oxygen, Dissolved	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328813

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

268

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 268 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Dissolved oxygen concentrations shall conform to those limits listed in Section 3.3.5. Section 3.3.5 lists dissolved oxygen concentration limits for COLD beneficial use waters to be a daily minimum of 6.0 mg/L and a 7-day moving average of 8.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2015-09-08 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158665, Oxygen, Dissolved	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328849

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Fish Spawning

Number of Samples:

268

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 268 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2015-09-08 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158665, Oxygen, Dissolved	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328808

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

463

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states: Dissolved oxygen concentrations shall conform to those limits listed in Section 3.3.5. Section 3.3.5 lists dissolved oxygen concentration limits for COLD beneficial use waters to be a daily minimum of 6.0 mg/L and a 7-day moving average of 8.0 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2013-02-13 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference


DECISION ID	163085	Region 1
Winchuck River HU, Gilbert 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. Zero samples exceeded the objectives, guidelines, or criteria for beneficial uses applicable to this water segment-pollutant combination, which is less than the minimum number of exceedances needed to place the water segment on the section CWA section 303(d) List for conventional or other pollutants (Table 3.2 of the Listing Policy). The data used satisfies the data quality requirements (section 6.1.4) and data quantity requirements (section 6.1.5) of the Listing Policy. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. 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.

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 163085, Specific Conductivity	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329145

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

190

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 190 samples exceeded the water quality threshold for SpecificConductivity.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Waters designated for use as domestic or municipal supply (MUN) shall not contain concentrations of chemical constituents in excess of the limits specified in California Code of Regulations, Title 22, Chapter 15, Division 4, Article 4, Section 64435 (Tables 2 and 3), and Section 64444.5 (Table 5), and listed in Table 3-2 of this Plan (Water Quality Control Plan, North Coast Basin).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the 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: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2010-11-15 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 163085, Specific Conductivity	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329164

Pollutant:

Specific Conductivity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

182

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 182 samples exceeded the water quality threshold for SpecificConductivity.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the 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: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2010-11-15 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference


DECISION ID	158667	Region 1
Winchuck River HU, Gilbert Creek

Pollutant:	Temperature, water
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. Zero of 371 samples exceed the COLD beneficial use objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 371 samples exceed the COLD beneficial use objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 158667, Temperature, water	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329283

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

190

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 190 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses. At no time or place shall the temperature of any COLD water be increased more than 5 degrees Fahrenheit (F) above natural receiving water temperature (Basin Plan, North Coast Region).

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to Carter (2008) the lethal temperature evaluation guideline for salmonid spawning, egg incubation & fry emergence is 20C.

Guideline Reference:

Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids. Implications for California's North Coast TMDLs. California Regional Water Quality Control Board, North Coast Region

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2010-11-15 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158667, Temperature, water	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329309

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

181

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 181 samples exceeded the water quality threshold for Temperature.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

According to Carter (2008) the lethal temperature evaluation guideline for salmonid spawning, egg incubation & fry emergence is 20C.

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2010-11-15 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference


DECISION ID	158668	Region 1
Winchuck River HU, Gilbert Creek

Pollutant:	Turbidity
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. Forty-two of 295 samples exceed the guideline. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the CWA section 303(d) List. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Forty-two of 295 samples exceed the guideline and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 158668, Turbidity	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329393

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

143

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 17 of 143 samples exceeded the water quality threshold for Turbidity.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the 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: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2015-09-08 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158668, Turbidity	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

329385

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

152

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 25 of 152 samples exceeded the water quality threshold for Turbidity.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

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: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2013-02-13 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference


DECISION ID	158666	Region 1
Winchuck River HU, Gilbert 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. Two lines of evidence are available in the administrative record to assess this pollutant. One of the 295 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. One of 295 samples exceeded the Objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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

State Board Review of Regional Board Conclusion and Recommendation:

State Board Decision Recommendation:

Line of Evidence (LOE) for Decision ID 158666, pH	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328905

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

152

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 1 of 152 samples exceeded the water quality threshold for pH.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, North Coast Basin, Chapter III, General Objectives for all Inland Surface Waters, Enclosed Bays and Estuaries states the following: For waters not mentioned by a specific beneficial use, the pH value shall not be depressed below 6.5 or raised above 8.5.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-2 (Gilbert Creek 2).

Temporal Representation:

The samples were collected between the dates of 2013-02-13 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference

Line of Evidence (LOE) for Decision ID 158666, pH	Region 1
Winchuck River HU, Gilbert Creek

LOE ID:

328906

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

143

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Tolowa Dee-ni Nation (Smith River Rancheria), California (Tribal) data for Winchuck River HU, Gilbert Creek to determine beneficial use support and results are as follows: 0 of 143 samples exceeded the water quality threshold for pH.

Data Reference:

WQX from the NWQMP for the 2026 Integrated Report in Region 1

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) for the North Coast Region

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: SRR_WQX-GC-3 (Gilbert Creek 3).

Temporal Representation:

The samples were collected between the dates of 2015-09-08 and 2022-08-25

Environmental Conditions:

QAPP Information:

Tolowa Dee-ni Nation (Smith River Rancheria) QA

QAPP Information Reference(s):

Data collected by a California Tribe QAPP Approved by U.S. EPA QAPP Reference