The SAB reviewed EPA’s draft report “A Field-Based Aquatic Life Benchmark for Conductivity in Central Appalachian Streams,” which uses field data to derive an aquatic life benchmark for conductivity. The benchmark is intended to protect 95% of aquatic species in streams in the Appalachian region influenced by mountaintop mining and valley fills. To protect water quality, EPA has identified a range of conductivity (a measure of the level of salt in the water) of 300 to 500 microSiemens per centimeter (uS/cm) that is generally consistent with protecting life in Appalachian streams. The maximum benchmark conductivity of 500 uS/cm is roughly five times above normal levels.
In their draft review, the SAB supports EPA’s scientific research and agrees with EPA’s conclusion that valley fills are associated with increased levels of conductivity in downstream waters, and that these increased levels of conductivity threaten stream life in surface waters. Following the completion of the external peer review and review of public comments, the report will be revised and published as a final report.
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