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DECISION ID |
7736 |
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| Pollutant: |
Mercury (tissue) |
| Final Listing Decision: |
List on 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: |
New Decision |
| Revision Status |
Revised |
| Sources: |
Mine Tailings |
| Expected TMDL Completion Date: |
2021 |
| Impairment from Pollutant or Pollution: |
Pollutant |
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| Weight of Evidence: |
This pollutant is being considered for listing under sections 3.5 of the Listing Policy. Under this section, a single line of evidence is necessary to assess listing status.
There is one line of evidence available in the administrative record to assess this pollutant. This evidence is a mercury in fish tissue dataset collected in 2004 for the Santa Clara Valley Water District to support Guadalupe River Watershed TMDL efforts in the Guadalupe River Watershed.
Based on the readily available data for this water body, the weight of evidence indicates that there is sufficient justification available in favor of adding this water segment-pollutant combination to the section 303(d) list in the Water Quality Limited Segments category.
This conclusion is based on the staff findings that:
1. The data concerning current conditions and supporting the listing decision satisfy the data quality requirements of section 6.1.4 of the Policy.
2. The available data satisfy the data quantity requirements of section 6.1.5 of the Policy.
3. Twenty of twenty samples exceeded the U.S. EPA fish tissue methylmercury criterion for the protection of 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. |
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| RWQCB Board Decision / Staff Recommendation: |
After review of the available data and information, Water Board staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are not met and mercury in fish tissue contributes to or causes the problem. This impairment will be addressed by the Guadalupe River Watershed TMDL. |
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| SWRCB Board Decision / Staff Recommendation: |
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| USEPA Decision: |
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| LOE ID: |
5739 |
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| Pollutant: |
Mercury (tissue) |
| LOE Subgroup: |
Pollutant-Tissue |
| Matrix: |
Tissue |
| Fraction: |
None |
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| Beneficial Use: |
Commercial or recreational collection of fish, shellfish, or organisms |
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| Number of Samples: |
20 |
| Number of Exceedances: |
20 |
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| Data and Information Type: |
Fish tissue analysis |
| Data Used to Assess Water Quality: |
The 20 fish tissue samples were collected in 2004 to support development of the Guadalupe River watershed mercury TMDL. The fish were all largemouth bass ranging in lengths from 330 to 500 mm and weighing between 520 and 2080 grams. The mercury concentrations ranged from 2.16 to 7.35 mg/kg. All 20 fish tissue samples exceeded the criterion. |
| Data Reference: |
Technical Memorandum 5.3.2 Data Collection Report, Volume II, prepared by TetraTech Inc. for Prepared for Santa Clara Valley Water District. February 8, 2005 |
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| Water Quality Objective/Criterion: |
The Basin Plan contains the following objective: 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.
In 2001, U.S. EPA adopted a fish tissue methylmercury criterion of 0.3 mg/kg (in whole fish) for the protection of human health. |
| Objective/Criterion Reference: |
Water Quality Criterion For The Protection of Human Health: Methylmercury 2002 303(d) List Update Reference # 87 |
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San Francisco Bay Basin (Region 2) Water Quality Control Plan (Basin Plan) |
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| Evaluation Guideline: |
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| Guideline Reference: |
Water Quality Criterion For The Protection of Human Health: Methylmercury 2002 303(d) List Update Reference # 87 |
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| Spatial Representation: |
These fish were caught throughout the reservoir, and fish of this size integrate spatially because they consume prey from a wide spatial range. |
| Temporal Representation: |
Fish tissue data were collected for this waterbody in late summer 2004. These adult fish integrate mercury concentrations over several years. |
| Environmental Conditions: |
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| QAPP Information: |
There is a well-developed QA plan for these data Tetra Tech, Inc. (Tetra Tech) 2003. Technical Memorandum 7.4.2, Quality Assurance Plan, Prepared for Santa Clara Valley Water District. June 13. |
| QAPP Information Reference(s): |
Technical Memorandum 7.4.2, Quality Assurance Plan, Prepared for Santa Clara Valley Water District. June 13 |