HELENA — A new federal Environmental Protection Agency study shows concentrations of toxic chemicals in fish tissue from lakes and reservoirs in nearly all 50 states, though those levels aren't considered dangerous in the Montana lakes tested.
According to the agency, the study marks the first time the EPA has been able to estimate the percentage of lakes and reservoirs nationwide that have fish containing potentially harmful levels of chemicals such as mercury and polychlorinated biphenyls, or PCBs.
The study sampled predator and bottom-feeding fish from 500 randomly selected lakes and reservoirs across the nation, including 16 in Montana. The EPA didn't provide specific data on the Montana lakes sampled, however nine of the 16 lakes are on Montana Fish, Wildlife & Parks' sport fish consumption chart, which advises anglers on the number of fish meals they can safely eat per month. None of the Montana lakes sampled contained fish with unsafe levels of mercury or PCBs.
The data show mercury concentrations in game fish exceeding EPA's recommended levels in 49 percent of lakes and reservoirs nationwide, and PCBs in game fish "at levels of potential concern" at 17 percent of lakes and reservoirs. According to the EPA, the findings are based on a comprehensive national study that used more data on levels of contamination in fish tissue than any previous study.
"These results reinforce (EPA Administrator Lisa) Jackson's strong call for revitalized protection of our nation's waterways and long-overdue action to protect the American people," Peter S. Silva, assistant administrator for EPA's Office of Water, said in a statement. "EPA is aggressively tackling the issues the report highlights. Before the results were even finalized, the agency initiated efforts to further reduce toxic mercury pollution and strengthen enforcement of the Clean Water Act — all part of a renewed effort to protect the nation's health and environment."
According to the Montana Department of Public Health and Human Services, more than 30 states and two Canadian provinces currently issue advisories because of mercury contaminated freshwater fish.
Fish in Montana generally have lower levels of contamination than in other states, according to the DPHHS. Montana has been testing fish in lakes and reservoirs for contaminants since 1994. The levels of contaminants found in Montana fish are generally low, but some locations fish contained levels of contaminants that are of concern for people who those fish on a frequent or prolonged basis.
Silver Creek, a tributary of Prickly Pear Creek northwest of Helena, has been limited to catch-and-release fishing because of high concentration of contaminants in fish, but the levels of contaminants in brook, rainbow and cutthroat trout, as well as perch and small panfish, in all other bodies of water in the state are considered low, according to the DPHHS' Montana Sport Fish Consumption Guidelines. The guidelines state that the most common Montana game fish species average less than 0.15 parts per million of methyl mercury. By comparison, commercially available canned tuna averages 0.17 to 0.20 parts per million of methyl mercury. That is a higher level of methyl mercury than virtually any rainbow trout or Kokanee salmon in Montana lakes and reservoirs, according to state officials.
EPA officials said the burning of fossil fuels, primarily coal, accounts for nearly half of mercury air emissions caused by human activity in the country, adding that those emissions are a significant contributor to mercury in bodies of water.
Agency officials said the emission of mercury into the air decreased by 58 percent from 1990 through 2005. The EPA is in the process of developing a new rule to reduce mercury emissions from power plants, and the Obama administration is actively supporting a new international agreement that would reduce mercury emissions worldwide.
According to the EPA, the health risk of consuming mercury by eating fish and shellfish is not a health concern for most people. However, some fish contain high levels of mercury that can harm the developing nervous system of unborn babies and young children. The agency advises pregnant women or those who may become pregnant, nursing mothers and young children to avoid eating some types of fish.