# Draft 2008 California 303(d)/305(b) Integrated Report

# Supporting Information

## Regional Board 5 - Central Valley Region

Water Body Name: | Slab Creek Reservoir (El Dorado County)
Water Body ID: | CAL5143201320080922153345
Water Body Type: | Lake & Reservoir

DECISION ID | 12117
Pollutant: | Mercury
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Resource Extraction
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Fourteen of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the 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. Fourteen of 31 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.
RWQCB Board Decision / Staff 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.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 12117

LOE ID: | 22616
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 30
Number of Exceedances: | 13
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Fish were sampled for tissue analysis at various locations from Slab Creek Reservoir. A total of 13 out of 30 samples exceeded the USEPA fish tissue criterion for human health. The average wet weight mercury concentration in fish tissue was 0.35 ppm for all 30 samples collected. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species: Brown Trout- 4 samples, 0.07-0.26 ppm (average 0.13 ppm), no exceedances; Rainbow Trout- 1 sample, 0.06 ppm, no exceedances; Sacramento Pikeminnow- 13 samples, 0.18-1.47 ppm (average 0.47 ppm), 6 exceedances; Sacramento Sucker- 12 samples, 0.18-0.45 ppm (average 0.31 ppm), 7 exceedances. All 30 samples were collected from fish with total lengths greater than 150 mm, which represent fish most commonly caught and consumed by sport fishers and their families.
Data Reference: | Upper American River Project, Slab Creek Reservoir Fish Tissue Bioaccumulation Study Report. Fish and Wildlife Water Pollution Control Laboratory, California Department of Fish and Game. Provided as an Appendix in the Final CEQA Supplement to the Sacramento Municipal Utility District Upper American River Project FERC Relicensing (FERC Project No. 2101). August 2008./Appendix_G_CDFG_Fish_Tissue_Samp_Rpt.pdf.
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: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
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 various locations from Slab Creek Reservoir. Site locations were not provided in the report.
Temporal Representation: | Fish samples were collected during two sampling events, on 7/10/2007 and 10/23/2007.
Environmental Conditions: | Significant gold mining activity occurred during the Gold Rush era within the Slab Creek Reservoir 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 Laboratory QAPP developed by the Fish and Wildlife Water Pollution Control Laboratory (CDFG, 2008). Mercury was analyzed in fish tissue according to the Laboratory Standard Operating Procedures (CDFG, 2006).
QAPP Information Reference(s):
LOE ID: | 22627
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | One Brown Trout sample was collected from one location from Slab Creek Reservoir. The wet weight mercury concentration of this fish tissue sample was 0.60 ppm, which exceeds the USEPA criterion. The sample was collected from a fish with a total length greater than 150 mm, which represents fish most commonly caught and consumed by sport fishers and their families.
Data Reference: | Sacramento Municipal Utility District, Upper American River Project (FERC Project No. 2101) and Pacific Gas and Electric Company, Chili Bar Project (FERC Project No. 2155). Water Quality Report. Version 3. May 2005
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: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
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: | The sample was collected at one location from Slab Creek Reservoir. The site location was not provided in the report.
Temporal Representation: | The fish sample was collected during one sampling event on 8/14/2003.
Environmental Conditions: | Significant gold mining activity occurred during the Gold Rush era within the Slab Creek Reservoir watershed (USGS, 2005).
QAPP Information: | Data quality: Unknown.. According to the report, sampling and analytical methods were done according to the State Water Resources Control Board Toxic Substances Monitoring Program. Mercury analyses in fish tissue were performed by Moss Landing Marine Laboratories. However, information about a QAPP used for this report was not provided.
QAPP Information Reference(s):