US EPA

This report adapts the standard U.S. EPA methodology for deriving ambient water quality criteria. Rather than use toxicity test results, the adaptation uses field data to determine the loss of 5% of genera from streams. The method is applied to derive effect benchmarks for dissolved salts as measured by conductivity in Central Appalachian streams using data from West Virginia and Kentucky.

This report uses field data to derive an aquatic life benchmark for conductivity. This benchmark value may be applied to waters in the Appalachian Region that are dominated by salts of SO₄^2- and HCO₃^- at circum neutral to mildly alkaline pH. This benchmark is intended to protect the biological integrity of waters in the region. It is derived by a method modeled on the U.S. EPA’s standard methodology for deriving water quality criteria. In particular, the methodology was adapted for use of field data. Field data were used because sufficient and appropriate laboratory data were not available and because high quality field data were available to relate conductivity to effects on biotic communities. This report provides scientific evidence for a conductivity benchmark in a specific region rather than for the entire United States.

This report provides scientific evidence for a conductivity benchmark in a specific region rather than for the entire United States.

Following the external peer review, the document will be revised and published as a final report.

U.S. EPA. A Field-Based Aquatic Life Benchmark for Conductivity in Central Appalachian Streams (2010) (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-10/023A, 2010.

Comments on this report may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the keyword EPA-HQ-ORD-2009-0934 (for the docket ID) to comment on this report.