Mining firms and state officials counter that past problems won't happen with future mines.
Pollution problems near the Boundary Waters are raising concerns about future Minnesota mining projects.
Environmental groups have found high concentrations of metals leaching into streams and wetlands from two long-closed sources: one old test mine and one abandoned mine. The pollution runs off waste rock excavated decades ago and piled at the sites.
Alerted by a resident near Ely, Friends of the Boundary Waters collected samples of the seeping water at one of the sites this summer.
An independent lab analysis confirmed that it contained arsenic, copper, nickel and iron at concentrations hundreds of times higher than state water quality standards allow for chronic exposure.
"These are toxic levels to animal life, and the arsenic is too high for humans," said Betsy Daub, policy director for Friends.
The findings come as several firms are on the verge of developing the first large mines in Minnesota in decades, investments that could climb into the billions. The mines would also be the first to extract and process copper, nickel and other precious metals instead of taconite.
Daub said the runoff should be a red flag for those future mines, especially those that would be within a few miles of the Boundary Waters.
The samples came from a small test mine that International Nickel Co. excavated in 1974. The waste rock remained in a pile that was covered. From it, water seeps across an area stained orange from the metals and into a nearby wetland about 3 miles from the Boundary Waters.
State pollution control officials said that the wetland dilutes the metals and that they consider the seepage minor.
"Sometimes it's damp, sometimes it's dry and sometimes there's a tiny bit of flow," said hydrogeologist Richard Clark of the Minnesota Pollution Control Agency (MPCA). "It doesn't reach our threshold for monitoring."
Daub said the seeping metals show that even on an extremely small scale, mining sulfide rock for copper, nickel and other precious metals will produce acid drainage and contamination that are too risky for the environment.
99 percent waste
Several mines are in the planning stages along a line stretching northeast from Hoyt Lakes past Babbitt toward Ely. The $600 million PolyMet project is the most advanced, with a formal proposal undergoing environmental review. Franconia Minerals, Duluth Metals and other firms have also identified deposits and are at various stages of engineering or feasibility studies.
Copper-nickel mines have produced acid drainage elsewhere in the country. Where sulfide ore is unearthed and exposed to air and water, it produces a weak sulfuric acid. The acid in turn dissolves the ore and releases heavy metals such as arsenic, copper, nickel, lead and mercury into nearby wetlands, streams and waters.
Geophysicist Dave Chambers reviewed the Friends' test mine results and said they're not surprising, since rain and snowmelt flow rapidly through porous piles of waste rock and leach out metals. Chambers works with the Center for Science in Public Participation in Bozeman, Mont., a nonprofit organization that gives technical advice about mining to regulatory agencies, businesses and environmental groups.
"In virtually every type of mine, over 99 percent of everything you mine becomes waste and is left right on the site as a waste pile of some sort," Chambers said. "When metals from the piles get into the water, they can be toxic to aquatic organisms at very low concentrations."
Acid mine drainage has not been a problem for taconite, which usually is contained in different ore that contains little or no sulfides.
An exception in Minnesota is the Dunka mine, a taconite mine near Babbitt that was covered with sulfide rock. LTV Steel Mining Co. operated the Dunka mine from 1964 to 1994 and stockpiled more than 20 million tons of waste rock. For decades the piles -- 80 to 100 feet high and extending for almost a mile -- have been leaching copper, nickel and other metals into wetlands and streams that flow into Birch Lake not far from the Boundary Waters. An average of 300,000 to 500,000 gallons runs off them each month, according to MPCA documents.
The Center for Biological Diversity and two other environmental groups charged in early 2010 that the runoff had violated state water standards nearly 300 times since 2005. The MPCA was also looking into the matter, and negotiated a $58,000 fine and cleanup agreement last March with Cliffs Erie, which now owns the site.
For Carla Arneson, who lives in the area, the fine was too small and the MPCA is "working the numbers" to make the pollution seem insignificant. "Our lakes are worth far more than any minerals that are going to be taken out of this state," she said.
Arneson said Dunka is an indicator of problems to come from the proposed PolyMet copper nickel mine a few miles away. Company officials have said they will put waste rock on synthetic liners to capture and treat any runoff. The project is receiving extra environmental study after an earlier review did not answer many questions about potential pollution.
New era of mines
Ann Foss, director of strategic projects for the MPCA, said that any copper-nickel mining will be scrutinized rigorously by both state and federal agencies. Firms will need to meet strict water-quality standards and provide financial assurance to protect the environment long after any mines are closed, she said.
"There will be a lot of analysis," Foss said. "There's a lot more required today than ever before."
Christopher Dundas, chairman of Duluth Metals Limited, said that historical problems have no bearing on or relevance to the underground copper-nickel mine that his firm is planning to develop in Minnesota. "This is a completely different era than what happened in the '60s," said Dundas. "Our operation will be state of the art and will be totally planned and designed to absolutely minimize every environmental issue."
However, Bruce Johnson, a former MPCA worker and DNR field chemist who worked on Dunka and other mining issues, said he fears that state agencies will shortcut environmental rules because of the intense political pressure to approve mines and put people to work. "I want to have good jobs, too, but I want to do it right," Johnson said. "These guys are going to make multi-millions of dollars. We don't want to be left with a bunch of mining pits full of polluted water that even ducks won't land on."
Tom Meersman • 612-673-7388