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

Supporting Information

Regional Board 2 - San Francisco Bay Region

Water Body Name:	Schell Creek (Sonoma County)
Water Body ID:	CAR2064005020110912155751
Water Body Type:	River & Stream


DECISION ID	143183	Region 2
Schell Creek (Sonoma County)

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:	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. 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:	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 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

298977

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 19 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. The temperature of any cold or warm freshwater habitat shall not be increased by more than 5 degrees F (2.8 degrees C) above natural receiving water temperature.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Scientific literature reviewed by the Washington Department of Ecology and U.S. EPA indicates that stream temperatures higher than 21C are associated with avoidance behavior and migration blockages in steelhead trout.

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

U.S. Environmental Protection Agency (USEPA). 2001. Issue Paper 1: Salmonid Behavior and Water Temperature Prepared as Part of EPA Region 10 Temperature Water Quality Criteria Guidance Development Project. Region 10, Seattle, WA. EPA-910-D-01-001 May 2001.

Guideline Reference:

Washington State Department of Ecology (WDOE). 2002. Evaluating Standards for Protecting Aquatic Life in Washington’s Surface Water Quality Standards: Temperature Criteria. Draft Discussion Paper and Literature Summary. Publication Number 00-10-070.

Guideline Reference:

Beschta RL, Bilby RE, Brown GW, Holtby LB, Hofstra TD. 1987. Stream temperature and aquatic habitat: Fisheries and forestry interactions. In: Salo EO, Cundy TW, eds. Streamside management: forestry and fishery interactions. College of Forest Resources, University of Washington, Seattle. Contribution No. 57. Proceedings of a Symposium held at University of Washington, February 12-14, 1986, pp. 191-231.

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2016-07-27 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

298547

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-30 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

299002

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Fish Migration

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

EPA Region 10 Guidance for Pacific Northwest State and Tribal Temperature Water Quality Standards. EPA 910-B-03-002. Region 10 Office of Water, Seattle, WA

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-30 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

289039

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 33 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Per Effects of Temperature, Dissolved Oxygen/Total Dissolved Gas, Ammonia, and pH on Salmonids (Carter 2008, Moyle 1976, and USEPA 1977), the lethal temperature evaluation guideline for both the steelhead adult migration and holding and the steelhead juvenile growth and rearing life stages is 24°C.

Guideline Reference:

Temperature criteria for freshwater fish: protocol and procedures. Ecological Research Series. EPA-600/3-77-061 (NTIS PB270032). Prepared by W.A. Brungs and B.R. Jones. U.S. Environmental Protection Agency, Washington, D.C

Guideline Reference:

Inland Fishes of California

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: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2016-07-20 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

289041

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Inland Fishes of California

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143183, Temperature, water	Region 2
Schell Creek (Sonoma County)

LOE ID:

288782

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Not Recorded

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Temperature.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Temperature objectives for surface waters are specified in the San Francisco Bay Regional Water Quality Control Plan. The following temperature objectives apply to surface waters: “- The natural receiving water temperature of inland surface waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such alteration in temperature does not adversely affect beneficial uses. - The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature.”

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Inland Fishes of California

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)


DECISION ID	143184	Region 2
Schell Creek (Sonoma County)

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 143184, Turbidity	Region 2
Schell Creek (Sonoma County)

LOE ID:

302823

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm 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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan for the San Francisco Bay Basin: Controllable water quality factors shall not cause a detrimental increase in concentrations of toxic substances found in bottom sediments or aquatic life. Effects on aquatic organisms, wildlife, and human health will be considered.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Turbidities of 40 NTU or greater can cause a reduced foraging efficiency and a shift in prey selection in piscivorous fish (largemouth bass) due to interference with their ability to find prey (Shoup, D.E. and Wahl D.H., 2009). The application of this evaluation guideline was restricted to the dry season (May to October) because runoff and resuspension of fine substrate during storm events may naturally elevate turbidity compared to baseflow conditions. The magnitude and duration of these increases will vary depending on the watershed’s geology and land use and may not represent a chronic turbidity problem. Turbidity is naturally higher in tidal river systems, so sample locations with salinity regimes (i.e., Freshwater or Marine) designated as “Marine” were excluded from this analysis.

Guideline Reference:

The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2019-06-24 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143184, Turbidity	Region 2
Schell Creek (Sonoma County)

LOE ID:

289800

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for Turbidity.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Sigler et al. (1984) states that turbidities of 25 NTUs or greater caused reduction in juvenile salmonid growth due to interference with their ability to find food. The application of this evaluation guideline was restricted to the dry season (May to October) because Coho and steelhead early life stages are present during the dry season and feeding becomes infrequent during the winter months (Moyle 2002). Additionally, runoff and resuspension of fine substrate during storm events may naturally elevate turbidity compared to baseflow conditions. The magnitude and duration of these increases will vary depending on the watershed’s geology and land use and may not represent a chronic turbidity problem. Turbidity is naturally higher in tidal river systems, so sample locations with salinity regimes (i.e., Freshwater or Marine) designated as “Marine” were excluded from this analysis.

Guideline Reference:

Effects of chronic turbidity on density and growth of steelheads and coho salmon. Transactions of the American Fisheries Society 113:142-150

Guideline Reference:

Inland Fishes of California

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2019-06-24 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)


DECISION ID	143182	Region 2
Schell Creek (Sonoma County)

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

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

State Board Review of Regional Board Conclusion and Recommendation:

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

Line of Evidence (LOE) for Decision ID 143182, pH	Region 2
Schell Creek (Sonoma County)

LOE ID:

287239

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for pH.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives, Section 3.3.9 pH states: The pH shall not be depressed below 6.5 nor raised above 8.5. This encompasses the pH range usually found in waters within the basin. Controllable water quality factors shall not cause changes greater than 0.5 units in normal ambient pH levels.

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-30 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143182, pH	Region 2
Schell Creek (Sonoma County)

LOE ID:

287025

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 3 samples exceeded the water quality threshold for pH.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-30 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143182, pH	Region 2
Schell Creek (Sonoma County)

LOE ID:

286986

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2016-07-27 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)


DECISION ID	143181	Region 2
Schell Creek (Sonoma County)

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

Regional Board Conclusion:	This pollutant is being considered for placement on the CWA section 303(d) List under section 3.2 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. Twelve of the forty-one samples exceed the Basin Plan dissolved oxygen objective for COLD beneficial uses. 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. Twelve of the forty-one samples exceed the Basin Plan dissolved oxygen objective for COLD beneficial uses 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:	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 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286211

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm 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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 7 of 31 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2016-08-03 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286234

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm 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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286296

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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286415

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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286441

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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 12 of 31 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as cold water habitat shall be of a 7.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the dates of 2016-08-03 and 2019-07-15

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 143181, Oxygen, Dissolved	Region 2
Schell Creek (Sonoma County)

LOE ID:

286130

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Warm 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 Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and results are as follows: 0 of 5 samples exceeded the water quality threshold for Oxygen, Dissolved.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Dissolved oxygen objectives for waters designated as warm water habitat shall be of a 5.0 mg/l minimum. (Water Quality Control Plan, San Francisco Bay Basin, Chapter III Water Quality Objectives.)

Objective/Criterion Reference:

Water Quality Control Plan (Basin Plan) San Francisco Bay Basin (Region 2)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site: 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the dates of 2019-01-23 and 2019-02-19

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)


DECISION ID	148718	Region 2
Schell Creek (Sonoma County)

Pollutant:	Indicator Bacteria
Final Listing Decision:	List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Sources:	Onsite Wastewater Systems (Septic Tanks)
TMDL Name:	Sonoma Creek Pathogens
TMDL Project Code:	63
Date TMDL Approved by USEPA:	02/09/2008
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Conclusion:	This pollutant is being considered for addition to the CWA section 303(d) List under sections 2.2 and Section 3.3 of the Listing Policy. Under section 3.3 of the Policy, a minimum of one line of evidence is needed to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Eight of eight samples exceed the E. coli geometric mean objective to protect water contact recreation. 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 from the CWA section 303(d) List. There is sufficient justification to place it in the Being Addressed portion of the CWA 303(d) List because a TMDL has been completed and approved by RWQCB and USEPA, and is expected to result in attainment of the standard. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Eight of eight samples exceed the E. coli geometric mean objective to protect water contact recreation and these exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. The Sonoma Creek Pathogens TMDL was approved by USEPA on 02/09/2008. 5. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should 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:	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 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

299935

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

GeoMean

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 6 of the 6 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

The bacteria water quality objective to protect the REC-1 beneficial use for waters where the salinity is equal to or less than 1 part per thousand 95 percent or more of the time applies a rolling six-week geometric mean of E. coli, not to exceed 100 cfu/100 mL (ISWEBE 2018).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the days of 2016-07-20 and 2019-07-15 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

300104

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 2 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the days of 2019-01-23 and 2019-02-19 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

299956

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

GeoMean

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the days of 2019-01-23 and 2019-02-19 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

299916

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

GeoMean

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the geomean water quality threshold for E. coli. This is a six week rolling geomean that is calculated weekly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH00904 (Schell Creek at San Luis Rd Above SVCSD).

Temporal Representation:

The samples were collected between the days of 2019-01-23 and 2019-02-19 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

300082

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 10 of the 14 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH009 (Schell Creek at Hwy 121).

Temporal Representation:

The samples were collected between the days of 2016-07-20 and 2019-07-15 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)

Line of Evidence (LOE) for Decision ID 148718, Indicator Bacteria	Region 2
Schell Creek (Sonoma County)

LOE ID:

300083

Pollutant:

Escherichia coli (E. coli)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

STV

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

PATHOGEN MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed Clean Streams in S. SoCo Pathogen Source Detection data for Schell Creek (Sonoma County) to determine beneficial use support and the results are as follows: 1 of the 2 samples exceeded the Statistical Threshold Value (STV) water quality threshold for E. coli. The STV is based on a 10% exceedance rate that is calculated monthly.

Data Reference:

Field, Habitat, WQ data from the California Environmental Data Exchange Network assembled for the 2024 Integrated Report in Region 2.

SWAMP Data:

Non-SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected at 1 monitoring site(s), station(s): 206SCH00903 (Schell CreekSchell Creek at 8th St Below SVCSD).

Temporal Representation:

The samples were collected between the days of 2019-01-23 and 2019-02-19 .

Environmental Conditions:

QAPP Information:

Sonoma County Permit and Resource Management Department. 2019. Clean Streams in Southern Sonoma County (CS3C).

QAPP Information Reference(s):

Clean Streams in Southern Sonoma County (CS3C)