According to a just-released U.S. Geological Survey (USGS) study, scientists detected mercury contamination in every fish sampled in 291 streams across the country. About one fourth of the fish sampled were found to “contain mercury at levels exceeding the criterion for the protection of people who consume average amounts of fish, established by the U.S. Environmental Protection Agency,” according to USGS. More than two-thirds of the fish exceeded the U.S. EPA level of concern for fish-eating mammals.

Mercury contamination of fish, ospreys, loons, and other aquatic-feeding animals continues to be a concern in the Adirondack region where the problem is the most acute of all New York State. New evidence in the Northeast shows mercury contamination in animals that only feed on land, spreading the concern from water based ecosystems to terrestrial ones as well.

A USGS press release laid out the threat: “Mercury, a neurotoxin, is one of the most serious contaminants threatening our nation’s waters. The main source of mercury to natural waters is mercury that is emitted to the atmosphere and deposited onto watersheds by precipitation. However, atmospheric mercury alone does not explain contamination in fish in our nation’s streams. Naturally occurring watershed features, like wetlands and forests, can enhance the conversion of mercury to the toxic form, methylmercury. Methylmercury is readily taken up by aquatic organisms, resulting in contamination in fish.”

The Adirondacks and Catskills are downwind of numerous coal-burning power plants, whose mercury emissions contribute significantly to mercury pollution. A 2007 independent study by the Charles Driscoll and the Hubbard Brook Research Foundation estimated that mercury emissions from U.S. coal-fired power plants are responsible for 40 percent to 65 percent of mercury deposition in the Northeast.

According to the Adirondack Mountain Club current levels of mercury deposition in the Northeast are four to six times higher than the levels recorded in 1900. Ninety-six percent of the lakes in the Adirondack region and 40 percent of the lakes in New Hampshire and Vermont exceed the recommended EPA action level for methyl mercury in fish. Mercury is also present in two-thirds of Adirondack loons at levels that negatively impact their reproductive capacity, posing a significant risk to their survival, the club says.

New York State recommends that no one eat more than one meal per week of fish taken from any lake, river, stream or pond in New York State. There is a complete (and disturbing) list and map of the Adirondack fish advisories from the New York State Department of Health located here. It lists 55 Adirondack lakes from which “children less than 15 years old and women who are pregnant or who might one day become pregnant should not eat any fish.”

All 50 states have mercury monitoring programs, and 48 states issued fish-consumption advisories for mercury in 2006, the most recent year of national-scale reporting to the EPA. The EPA regulates mercury emissions to air, land and water. In February the U.S. Supreme Court rejected a last ditch attempt by the Bush administration to weaken controls on mercury pollution nationwide. The EPA has announced that it intends to control air emissions of mercury from coal-fired power plants by issuing a rule under the Clean Air Act.