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

# Supporting Information

## Regional Board 5 - Central Valley Region

Water Body Name: | Folsom Lake
Water Body ID: | CAL5142301020080702152603
Water Body Type: | Lake & Reservoir

DECISION ID | 12948
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: | 2019
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. Forty-one 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. Forty-one of 62 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 12948

LOE ID: | 22543
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: | 61
Number of Exceedances: | 40
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Asses Water Quality: | Fish were sampled for tissue analysis at multiple locations throughout Folsom Lake. A total of 40 out of 61 samples exceeded the USEPA fish tissue criterion for human health. The average wet weight mercury concentration in fish tissue was 0.47 ppm for all 61 samples collected. The number of fish collected per sample, the measured mercury concentrations in fish tissue, and the number of exceedances are, by species: Bluegill- 4 samples, 0.1-0.18 ppm (average 0.14 ppm), no exceedances; Channel Catfish- 10 samples, 0.37-0.65 ppm (average 0.51 ppm), 10 exceedances; Chinook Salmon- 4 samples, 0.47-1 ppm (average 0.78 ppm), 4 exceedances; Green Sunfish- 1 sample, 0.33 ppm, 1 exceedance; Largemouth Bass- 6 samples, 0.47-0.98 ppm (average 0.71 ppm), 6 exceedances; Rainbow Trout- 6 samples, 0.1-0.91 ppm (average 0.32 ppm), 2 exceedances; Smallmouth Bass- 1 sample, 0.51 ppm, 1 exceedance; Spotted Bass- 15 samples, 0.36-1.2 ppm (average 0.69 ppm), 15 exceedances; Trout- 13 samples, 0.03-0.2 ppm (average 0.1 ppm), no exceedances; White Catfish- 1 sample, 1 ppm, 1 exceedance. All 61 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: | United States Bureau of Reclamation Mercury Fish Study for Folsom and New Melones Reservoirs, 2004-2006. United States Bureau of Reclamation, Mid-Pacific Region, Environmental Monitoring Branch. Unpublished Data
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 multiple locations throughout Folsom Lake. Site locations were not provided with the submitted data.
Temporal Representation: | Fish samples were collected during three sampling events from 7/29/2004 to 8/18/2004, and two sampling events from 6/17/2006 to 8/4/2006.
Environmental Conditions: | Significant gold mining activity occurred during the Gold Rush era within the Folsom Lake watershed and the lands inundated by Folsom Lake (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 QAPP for the Survey of Mercury Content in Fish from Folsom Lake and New Melones Reservoir (USBR, 2004).
QAPP Information Reference(s):
LOE ID: | 22544
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 5-fish composite sample of Largemouth Bass was collected at one location from Folsom Lake. The wet weight mercury concentration of this fish tissue sample was 0.33 ppm, which exceeds the USEPA criterion. The composite sample was collected from fish with total lengths greater than 150 mm, which represents fish most commonly caught and consumed by sport fishers and their families.
Data Reference: | SWRCB-DWQ. 2002. Toxic Substances Monitoring Program: Freshwater Bioaccumulation Monitoring: TSM Program Data 1978-2000. State Water Resources Control Board, Division of Water Quality
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 Folsom Lake near the dam.
Temporal Representation: | The fish sample was collected on 10/2/1981.
Environmental Conditions: | Significant gold mining activity occurred during the Gold Rush era within the Folsom Lake watershed and the lands inundated by Folsom Lake (USGS, 2005).
QAPP Information: | Data quality: Good.. Quality Control for the fish sampling, tissue preparation, mercury analysis, and QA sample analysis portions of this study was conducted as described in the Toxic Substance Monitoring Report for 1981 (La Karo et al., 1982).
QAPP Information Reference(s):