© Bernie KasperFoam on a stream in southeast Indiana.
INDIANAPOLIS - Six of every 100 streams in Indiana contain mercury at levels greater than the state water quality standard protecting human health, according to research released today by the U.S. Geological Survey. With new mapping techniques, the scientists identified an area in southeastern Indiana with some of the highest levels of mercury deposition in the United States.
Mercury concentrations in 73 percent of the samples exceeded the more restrictive state water quality standard protecting wildlife.
More than 80 percent of the water samples had detectable methylmercury, the most toxic form of mercury that accumulates in fish, birds, and mammals at the top of food chains.
In a separate report looking at mercury in rain and snow, USGS scientists found that mercury concentrations in more than 40 percent of the samples exceeded the Indiana water quality standard for human health and nearly all concentrations exceeded the standard protecting wildlife. "Our studies are showing that mercury can be found in the water everywhere we've looked in Indiana
, but the mercury varies from place to place and changes both seasonally and year to year," said USGS scientist Martin Risch, an author on both papers.