Toxic runoff from an old test mine in northeastern Minnesota may threaten nearby lakes and streams, an environmental group warned.
Friends of the Boundary Waters Wilderness said it found toxic metals in water samples from the old copper exploration site about 15 miles southeast of Ely, just a couple miles from the Boundary Waters Canoe Area.
The group contends that state regulators have ignored the old site for more than 30 years. The site is near some current copper exploration sites and proposed mines, and the group said its findings show that mining Minnesota's copper-bearing rock could cause a pollution problem.
Richard Clark, a hydrogeologist with the Minnesota Pollution Control Agency, told the Duluth News Tribune for a story published Tuesday that publicity about the study might prompt his agency and the Department of Natural Resources to retest the site.
Clark said the lab results "make sense, they don't surprise me." But he also said a recent inspection showed little or no runoff reaching nearby streams.
"The levels of copper, nickel, iron and arsenic are all in violation" of state water quality standards, Betsy Daub, policy director of the group, told the News Tribune. "We don't know if the runoff is reaching the Kawishiwi River or not, or if it's causing any damage, because the state hasn't been monitoring the problem for more than 30 years."
Neither the PCA nor DNR has actually taken samples at the site since 1976.
Clark said he visited the site two weeks ago when concerns were first brought to his attention and that he found it dry, with no runoff. He said he's been there several times in recent years and not seen any environmental damage as rainwater percolates through a pile of waste rock from the test mine and slowly seeps out.
"There was a report issued in 1974 when the mining was completed that said the volume and nature of the discharge at that site didn't pose any threat" to nearby waterways, Clark said. "The decision in the 1970s (not to conduct further tests) predates my arrival here. But it's my guess that report is why testing was discontinued."
The small test mining was conducted in 1974 by International Nickel Co. to look for copper and other valuable metals. Recent exploration by other companies have found vast deposits of copper, nickel, platinum and other metals.
Friends of the Boundary Waters Wilderness is concerned because when copper-bearing rock is exposed to air and water during mining, it can leach sulfuric acid that can damage streams and aquatic life.
Several supporters of copper mining in Minnesota, including mining company geologists, have said the rock near Ely is too low in sulfur to cause acid runoff. But Daub said her group's findings call those claims into question.
"We now know we are getting acid drainage where the companies are saying we would not get it," Daub said. "This was a small test site of about 10,000 tons total and it's causing acid runoff decades later. Twin Metals is proposing mining 40,000 tons per day."
Frank Ongaro, executive director of the industry group Mining Minnesota, told the News Tribune that even if the new findings are accurate, they will have little bearing on future mining operations because so much about mining has changed.
"This was 36 years ago, pre-environmental review ... and pre-mineland reclamation laws," Ongaro said. "Projects being proposed now will have to demonstrate that they can mine process and handle their waste and still meet Minnesota standards or they will not get a permit. These projects are being engineered precisely to address all the waste issues that may arise from any mining operation."
Information from: Duluth News Tribune
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