Proposed changes to Kentucky selenium water quality standards

The February 2013 proposal by the Beshear administration to weaken the selenium water quality standard violates the law and endangers wildlife.

Kentucky’s current selenium water quality standards set an acute (1-hour) limit of 20 μg/L in the water column and a chronic (4-day average) limit of 5 μg/L in the water column.

The Kentucky Division of Water has proposed changing the standards to an acute limit of 258 μg/L in water (or higher depending on sulfate concentration), and a chronic standard based on the concentration of selenium in fish tissue.

The proposed acute standard harms fish and wildlife

The proposed acute standard is identical to a standard that U.S. EPA declined to adopt in 2004 after receiving overwhelming criticism from scientists:

  • The U.S. Fish and Wildlife Service objected to EPA’s proposed standard because it fails to account for the dramatic impacts on the food web from short-lived but high-concentration discharges;
  • Studies show that short selenium spikes at levels less than five percent of the proposed standard lead to dangerous levels of selenium higher up the food chain that persist long after the spike


The proposed acute standard also ignores the overwhelming science by allowing for even higher discharges of selenium if sulfate is also present in the discharge:

  • The U.S. Fish and Wildlife Service has previously objected to this approach by noting that sulfate has never been shown to mitigate selenium toxicity in the field.

The proposed chronic standard is flawed, unenforceable, and harms fish and wildlife

The proposed chronic fish tissue standard (8.6 μg/g) is even higher than a similar standard that EPA considered and
rejected, and is based on flawed science

  • The standard was developed under guidelines that were not intended for use with toxins like selenium that bioaccumulate in the food chain;
  • The standard will not protect selenium sensitive species that are important to Kentucky like bluegill, sunfish and catfish.

The proposed chronic fish tissue standard is unenforceable

  • The fish tissue approach won’t protect streams where fish are absent, leaving salamanders, crayfish, and key parts of the food chain at risk;
  • There is no way to use the chronic standard to set effective limits in a discharge permit for a new operation.