| Water Body Name: | Lexington Reservoir |
| Water Body ID: | CAL2054002020000304130209 |
| Water Body Type: | Lake & Reservoir |
DECISION ID |
98169 |
Region 2 |
Lexington Reservoir |
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| Pollutant: | Mercury |
| Final Listing Decision: | List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2016) |
| Revision Status | Original |
| Sources: | A Source Unknown |
| Expected TMDL Completion Date: | 2029 |
| 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 3.4 of the Listing Policy. Under section 3.4 a single line of evidence is necessary to assess listing status in addition to the presence of a fish consumption advisory for the waterbody.
One line of evidence is available in the administrative record to assess this pollutant. Twenty-seven of fifty-one samples exceed the OEHHA guideline. 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. Twenty-seven of fifty-one samples exceed the OEHHA guideline and there is a fish consumption advisory in effect for this waterbody, and this exceeds the allowable frequency described in section 3.4 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. |
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| LOE ID: | 92134 | ||||
| Pollutant: | Mercury | ||||
| LOE Subgroup: | Pollutant-Tissue | ||||
| Matrix: | Tissue | ||||
| Fraction: | Fish fillet | ||||
| Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms | ||||
| Number of Samples: | 51 | ||||
| Number of Exceedances: | 27 | ||||
| Data and Information Type: | Fish tissue analysis | ||||
| Data Used to Assess Water Quality: | Twenty-seven of the 51 samples exceeded the guideline. None of the twenty, 1-year old largemouth bass collected in 2004 exceeded the guideline. All eleven adult largemouth bass collected in 2004 exceeded the guideline. Data for 2006 were reported on a dry weight basis and were converted to a wet weight basis by multiplying the dry-weight concentration by a factor of 1 minus the percentage of moisture content expressed as a decimal. The data for 2004 were assumed to be reported on a wet-weight basis. Only the muscle tissue samples analyzed with the skin-off were used to assess the commercial beneficial use. | ||||
| Data Reference: | Data from the Guadalupe River Watershed Mercury TMDL project, Aug. 2004-Nov 2006 | ||||
| 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. Many pollutants can accumulate on particles, in sediment, or bioaccumulate in fish and other aquatic organisms. 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: | The OEHHA (2008) fish contaminant goal is 220 ppb. This screening level assumes an average body weight of 70 kg and a consumption rate of 32 g/day. Total mercury is assumed to be 100% methylmercury. The more conservative reference dose of 1x10-4 mg/kg-day. | ||||
| Guideline Reference: | Development of Fish Contaminant Goals and Advisory Tissue Levels for Common Contaminants in California Sport Fish: Chlordane, DDTs, Dieldrin, Methylmercury, PCBs, Selenium, and Toxaphene | ||||
| Spatial Representation: | Samples were collected in Lexington Reservoir. | ||||
| Temporal Representation: | Samples were collected on 11/14/2006 and on 9/8/2004. | ||||
| Environmental Conditions: | |||||
| QAPP Information: | Samples were collected in accordance with the Quality Assurance Plan prepared on June 13, 2003 for the Santa Clara Valley Water District per Agreement No. A2643G, the Guadalupe River Watershed Mercury TMDL Project. | ||||
| QAPP Information Reference(s): | |||||