Draft California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name: Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
Water Body ID: CAR5133201020080623175316
Water Body Type: River & Stream
 
DECISION ID
131886
Region 5     
Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
 
Pollutant: Mercury
Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: Do Not Delist from 303(d) list (TMDL required list)(2018)
Revision Status Revised
Sources: A Source Unknown
Expected TMDL Completion Date: 2027
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the section 303(d) list under section 3.11 of the Listing Policy. Under section 3.11 when all other listing factors do not result in the listing of a water segment but information indicates non-attainment of standards, a water segment shall be evaluated to determine whether the weight of evidence demonstrates that water quality standard is not attained. If the weight of evidence indicates non-attainment, the water segment shall be placed on the CWA section 303(d) List.
Two lines of evidence are available in the administrative record to assess this pollutant.

LOEs 95474 and 22622 are replaced with LOEs 227034 and 227035. The replacement LOEs are reassessments of the same data following the statewide mercury objectives adopted in 2017.
The assessment in LOEs 95474 and22622 is for human health, however the data has been reassessed for the WILD beneficial use due to length of fish in the sample.
WILD beneficial use (prey fish objective):
LOE 227034: 1 of 1 samples exceed the mercury objective and consist of # fish that can be a mixture of trophic levels collected between February and July of the same calendar year.
LOE 227035: 1 of 1 samples exceed the mercury objective and consist of # fish that can be a mixture of trophic levels collected between February and July of the same calendar year.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the CWA section 303(d) List.

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. Tissue samples were compared with the prey fish objective and 2 of 2 samples exceed the WILD beneficial use. Samples may consist of a mix of trophic levels and are from a minimum of 2 annual averages and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
A minimum of 3 annual averages based on composite fish tissue samples must meet the standard to indicate attainment of the standard.
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 decision was made by SWRCB staff.
 
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 131886, Mercury
Region 5     
Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
 
LOE ID: 227035
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Tissue
Matrix: Tissue
Fraction: Fish fillet
 
Beneficial Use: Wildlife Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed CALFED data for Davis Creek (downstream from Davis Creek Reservoir, Yolo County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Mercury. All fish collected between February and July of the same calendar year with a reported length of 50-150 mm were averaged into a single sample, independent or species of trophic level, for comparison with the objective. This LOE consists of a total of 38 fish, which were aggregated into 1 annual averages, consisting of 3 fish species (1 composite(s) of California Roach each composed of 10 fish per composite, 1 composite(s) of California Roach each composed of 4 fish per composite, 3 composite(s) of Speckled Dace each composed of 8 fish per composite). Of these annual averages, 1 average(s), (Year(s): 2001) exceeded the objective.
Data Reference: Mercury Bioaccumulation and Trophic Transfer in the Cache Creek Watershed, California, in Relation to Diverse Aqueous Mercury Exposure Conditions. CALFED Mercury Program Final Project Report. January 25, 2004
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. (Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Statewide Prey Fish Water Quality Objective for the protection of Wildlife Habitat comes from the Statewide Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California, and is 0.05 mg/Kg wet weight whole fish samples of any fish species between 50 to 150 mm in total length collected between February 1 and July 31. (SWRCB Resolution No. 2017-0027)
Guideline 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
 
Spatial Representation: Data was collected from 1 station(s) with the station code(s): Davis Ck. At Cache.
Temporal Representation: Data for this line of evidence were collected between 2001-05-08 and 2001-05-08. When composited fish were collected over multiple days, the first day of fish collection was used as the sample date in the LOE, both for LOE writing, and for averaging period purposes.
Environmental Conditions:
QAPP Information: Data quality: Excellent. Quality Control for all of the elements described in section 6.1.4 of the Policy was conducted in accordance with the CALFED Mercury Project QAPP (Puckett and van Buuren, 2000).
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.
 
Line of Evidence (LOE) for Decision ID 131886, Mercury
Region 5     
Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
 
LOE ID: 227034
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Tissue
Matrix: Tissue
Fraction: Fish fillet
 
Beneficial Use: Wildlife Habitat
 
Number of Samples: 1
Number of Exceedances: 1
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Water Board staff assessed CALFED data for Davis Creek (downstream from Davis Creek Reservoir, Yolo County) to determine beneficial use support and the results are as follows: 1 of the 1 samples exceeded the water quality threshold for Mercury. All fish collected between February and July of the same calendar year with a reported length of 50-150 mm were averaged into a single sample, independent or species of trophic level, for comparison with the objective. This LOE consists of a total of 71 fish, which were aggregated into 1 annual averages, consisting of 3 fish species (3 composite(s) of California Roach each composed of 9 fish per composite, 3 composite(s) of California Roach each composed of 10 fish per composite, 2 composite(s) of California Roach each composed of 7 fish per composite). Of these annual averages, 1 average(s), (Year(s): 2000) exceeded the objective.
Data Reference: Mercury Bioaccumulation and Trophic Transfer in the Cache Creek Watershed, California, in Relation to Diverse Aqueous Mercury Exposure Conditions. CALFED Mercury Program Final Project Report. January 25, 2004
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, animal, or aquatic life. (Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins)
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline: The Statewide Prey Fish Water Quality Objective for the protection of Wildlife Habitat comes from the Statewide Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California, and is 0.05 mg/Kg wet weight whole fish samples of any fish species between 50 to 150 mm in total length collected between February 1 and July 31. (SWRCB Resolution No. 2017-0027)
Guideline 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
 
Spatial Representation: Data was collected from 1 station(s) with the station code(s): Davis Creek below DCR.
Temporal Representation: Data for this line of evidence were collected between 2000-03-10 and 2000-05-17. When composited fish were collected over multiple days, the first day of fish collection was used as the sample date in the LOE, both for LOE writing, and for averaging period purposes.
Environmental Conditions:
QAPP Information: Data quality: Excellent. Quality Control for all of the elements described in section 6.1.4 of the Policy was conducted in accordance with the CALFED Mercury Project QAPP (Puckett and van Buuren, 2000).
QAPP Information Reference(s): This is a placeholder reference for data that was collected after QAPP requirements were developed, but exempt from the requirements.