Muncie, IN — One in eight fish taken from Indiana waterways and analyzed over a five-year period was tainted with the toxic metal mercury, according to federal scientists who last year reported that precipitation that falls near southeastern Indiana's coal-fired power plants harbors some of the nation's highest concentrations of atmospheric mercury.
The study led by U.S. Geological Survey hydrologist Martin Risch also showed that mercury contamination in both surface waters and fish across Indiana routinely exceeds levels recommended to protect humans and animals. Risch said the front cover of the mercury report includes photographs of an eagle and a boy holding a big fish.
"The young person needs to be told how many big fish he can eat to protect his health," Risch told The Star Press of Muncie.
Mercury released by coal-fired plants, metals industries and other sources enters the food chain and can accumulate in fish species that humans eat. Women who eat tainted fish during pregnancy or while breast-feeding can unknowingly lower their child's intelligence because mercury is a potent neurotoxin that harms the developing brain and can cause other problems.
The study covered samples taken between 2001 and 2006 and was done in partnership with the Indiana Department of Environmental Management. It also found 96 percent of discharged wastewater sampled in the state contained mercury, most of which exceeded federal standards.
A map of Indiana in the report shows hundreds of red dots at river and stream sites across the state where sampling found mercury-contaminated fish.
In 2005, coal-fired power plants were responsible for 58 percent of all mercury emissions into Indiana's air. The other largest contributors were steel mills and cement plants.
Risch said the most significant source of mercury in Indiana's watersheds is fallout from the air. He said the amount of mercury in rain and snow was the main factor affecting the heavy metal's presence in watersheds.
"It is largely believed that if you reduce mercury in the air you will eventually reduce the amount of mercury in the fish, and the only way we can know this is to measure it," Risch said. "We should be able to look later and see if the regulation of mercury emissions has an effect."
Ball State University's coal-fired power plant emitted 16 pounds of mercury into the air during 2005. During that same year, three and a half to four tons of mercury were emitted statewide, he said.
Risch noted that Ball State's relatively small mercury emissions will go down when it finishes switching to geothermal heating and cooling and shutters its coal power plant.
Municipal wastewater treatment plants also release mercury in the effluent discharged into waterways, but power plants are the main contributor.
Several common household and toiletry products contain levels of mercury that could account for part of that contamination, but most of the mercury is attributed to human waste, according to the report. And some mercury in wastewater could be attributed to dentists' offices.
Evansville television station WFIE reported that water and fish samples taken on the Wabash and White rivers in Vincennes and Petersburg in Indiana and Mount Carmel, Ill., had the highest mercury levels in the state. Seventeen percent of fish in Mount Carmel, 24 percent in Petersburg and 30 percent of fish in the Vincennes watershed had levels of mercury that exceeded safety standards.
In a more concentrated area near Petersburg, 45 percent of fish had unsafe mercury readings.
Evansville Water Superintendent Roger Johnson said even though the study paints a frightening picture, water from the tap is safe to drink.
"At least in the last nine years that we went back real quick and checked records, the levels have been non-detectable at all," Johnson said.
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