Final California 2018 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
74548
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)(2016)
Revision Status Original
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 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status.

One line of evidence is available in the administrative record to assess this pollutant. Seventeen of the 20 samples exceed the water quality objective.

LOE 22622 was not used in the final listing decision because of a criterion change. The data in LOE 22622 were reassessed in LOE 95474 with the new criterion. LOE 95474 was used in the final listing decision.


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 section 303(d) list in the Water Quality Limited Segments category.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Seventeen of 20 samples exceed the USEPA fish tissue criterion for human health and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: 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 74548, Mercury
Region 5     
Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
 
LOE ID: 95474
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Tissue
Matrix: Tissue
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 20
Number of Exceedances: 17
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Fish were sampled for tissue analysis at two locations from this reach. A total of 17 out of 20 samples exceeded the USEPA fish tissue criterion for human health. All 20 samples were analyzed as whole fish samples, which were translated to a filet concentration by multiplying the whole body concentration by 1.62 (Peterson et al, 2007).

1) Davis Creek below Davis Creek Reservoir: The average wet weight mercury concentration in fish tissue was 0.79 ppm for the 14 samples collected at this location. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species:

California Roach- 13 composite samples, 0.57-0.85 ppm (average 0.69 ppm), 13 exceedances;
Sacramento Sucker- one 11-fish composite sample, 2.14 ppm, 1 exceedance.

2) Davis Creek at Cache Creek: The average wet weight mercury concentration in fish tissue was 0.24 ppm for the 6 samples collected at this location. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species:

California Roach- 3 composite samples, 0.16-0.38 ppm (average 0.24 ppm), 1 exceedance;
Speckled Dace- 3 composite samples, 0.21-0.25 ppm (average 0.23 ppm), 3 exceedances.

All 20 composite samples were collected from fish with average total lengths less than 150 mm.
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 produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
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 U.S. EPA 304(a)-recommended water quality criterion for concentrations of methylmercury in fish tissue of trophic level 4 fish (150 - 500 mm; fillet wet weight) is 0.20 mg/Kg.
Guideline Reference: Water Quality Criterion for the Protection of Human Health: Methylmercury. Final. United States Environmental Protection Agency Office of Science and Technology Office of Water. EPA-823-R-01-001. January 2001
 
Spatial Representation: Samples were collected at two locations from this reach of Davis Creek: just downstream of the spillway from Davis Creek Reservoir; and just upstream of its confluence with Cache Creek.
Temporal Representation: Fish samples were collected during six sampling events from 3/10/2000 to 5/8/2001.
Environmental Conditions: Significant mercury mining activity occurred within the Davis Creek watershed (USGS, 2005).
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):
 
Line of Evidence (LOE) for Decision ID 74548, Mercury
Region 5     
Davis Creek (downstream from Davis Creek Reservoir, Yolo County)
 
LOE ID: 22622
 
Pollutant: Mercury
LOE Subgroup: Pollutant-Tissue
Matrix: Tissue
Fraction: Total
 
Beneficial Use: Commercial or recreational collection of fish, shellfish, or organisms
 
Number of Samples: 20
Number of Exceedances: 15
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: Fish were sampled for tissue analysis at two locations from this reach. A total of 15 out of 20 samples exceeded the USEPA fish tissue criterion for human health. All 20 samples were analyzed as whole fish samples, which were translated to a filet concentration by multiplying the whole body concentration by 1.62 (Peterson et al, 2007). 1) Davis Creek below Davis Creek Reservoir: The average wet weight mercury concentration in fish tissue was 0.79 ppm for the 14 samples collected at this location. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species: California Roach- 13 composite samples, 0.57-0.85 ppm (average 0.69 ppm), 13 exceedances; Sacramento Sucker- one 11-fish composite sample, 2.14 ppm, 1 exceedance. 2) Davis Creek at Cache Creek: The average wet weight mercury concentration in fish tissue was 0.24 ppm for the 6 samples collected at this location. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species: California Roach- 3 composite samples, 0.16-0.38 ppm (average 0.24 ppm), 1 exceedance; Speckled Dace- 3 composite samples, 0.21-0.25 ppm (average 0.23 ppm), no exceedances. All 20 composite samples were collected from fish with average total lengths less than 150 mm.
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 produce detrimental physiological responses in human, plant, animal, or aquatic life. The objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances.
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 USEPA Fish Tissue Residue Criterion for methylmercury in fish is 0.3 mg/kg (0.3 ppm) for the protection of human health. This is the concentration in fish tissue that should not be exceeded based on a total fish and shellfish consumption-weighted rate of 0.0175 kg fish/day. (USEPA, 2001)
Guideline Reference: Water Quality Criterion for the Protection of Human Health: Methylmercury. Final. United States Environmental Protection Agency Office of Science and Technology Office of Water. EPA-823-R-01-001. January 2001
 
Spatial Representation: Samples were collected at two locations from this reach of Davis Creek: just downstream of the spillway from Davis Creek Reservoir; and just upstream of its confluence with Cache Creek.
Temporal Representation: Fish samples were collected during six sampling events from 3/10/2000 to 5/8/2001.
Environmental Conditions: Significant mercury mining activity occurred within the Davis Creek watershed (USGS, 2005).
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):