Selenium a Threat to Ducks at the Great Salt Lake

Photo: © Greg Lavaty

Northern Shoveler. Photo: © Greg Lavaty

Selenium a Threat to Ducks at the Great Salt Lake The State of Utah recently proposed a new rule on the discharge of selenium into the Great Salt Lake to protect nesting waterfowl. The rule was prompted by mining activities and agricultural runoff, which have the potential to increase selenium concentrations to toxic levels over the next few years.

Selenium contamination of wetlands has been a problem in much of the arid West due to its presence in agricultural drainage and irrigation runoff. In 1982, deformed duck embryos at Kesterson National Wildlife Refuge in California caused the closure of the refuge. Ever since, FWS has carefully monitored selenium buildup in rivers and wetlands throughout the United States.

Utah has proposed a selenium limit of ten parts per million in the Great Salt Lake, which lab studies have shown will protect 90% of mallard eggs. However, FWS stated that this level needs to be halved to protect 100% of duck embryos, as required under the Migratory Bird Treaty Act.

The Great Salt Lake is an ABC-designated Globally Important Bird Area because of its significance as a stopover site for millions of migrating waterbirds, including ducks, shorebirds, and grebes, but this case goes beyond the health of the lake itself. The Utah decision will set a precedent for selenium discharges throughout the United States, including California’s Central Valley, the Salton Sea, and discharges from mountaintop coal mining in Appalachia (see article on page 15). In 2005, EPA approved selenium discharges from mountaintop coal mining over the objections of FWS and USDA Forest Service scientists. This decision allowed the continued mining and discharge into rivers without costly cleanup of the selenium contamination.

The EPA Office of Water must now make a decision on the Utah rule, which is expected before the end of 2009.