After four years and $22 million, PolyMet Mining Corporation's proposed copper mine in northeastern Minnesota cleared a major hurdle Thursday, when the U.S. Environmental Protection Agency gave plans for the controversial project a passing grade.

The rating means that federal regulators still have concerns about potential environmental effects of the proposed $650 million project and that they want to see more analysis and a clearer explanation of how pollution problems will be resolved. Specifically, they asked for more detail on issues that have dogged the project for months: how long contaminated water will have to be treated in future decades and how PolyMet's "financial assurance" will protect the state against unforeseen financial and environmental costs.

But it is far better than the failing grade they gave PolyMet's first environmental study four years ago, and it's on a par with grades received by other recent big projects in Minnesota, including the Central Corridor light-rail line and the new bridge over the St. Croix River.

"The EPA review provides feedback and guidance," said Jon Cherry, PolyMet's chief executive officer. " We will continue to work with the [agencies] to ensure they receive additional data or information that might be required."

The EPA's comments, delivered Thursday as state regulators closed their 90-day public comment period on PolyMet's environmental impact statement, are perhaps the most pivotal of the more than 49,000 that have been submitted. That's the largest number of comments the state has received on such a project — by a factor of 10 — and a reflection of the deep and clashing viewpoints the project has elicited statewide and the questions it raises about the future of what many deem the most beautiful corner of Minnesota.

"This has been a unique public review period," said Steve Colvin, who managed the environmental review for the Minnesota Department of Natural Resources. "The dialogue has been civil and productive and constructive."

And it's not over. A spokesman for PolyMet said the company hopes to start construction next year. But the EPA's review is not the end of what could still be a complex regulatory review, said Alexandra Klass, professor of environmental law at the University of Minnesota. The state could take months to put together a final environmental impact statement, an environmental group could take the state to court and then the project must still complete a crucial permitting phase, where concrete decisions are made.

"I don't think all the dominoes fall into place because you pass that point," Klass said. "It's still a long haul."

New form of mining

PolyMet, a Canadian minerals company, has proposed an open pit mine and processing facility near Babbitt and Hoyt Lakes in northeast Minnesota. It is just one of many companies hoping to tap into a massive deposit of copper, nickel and other precious metals that stretches up to the edge of the Boundary Waters Canoe Area Wilderness. PolyMet's plan has raised hopes of an economic renaissance in northern Minnesota, but environmental watchdog groups and Minnesota Indian tribes have raised alarms about its potential environmental effects.

Copper mining carries different and greater environmental risks to water than Minnesota's long-standing taconite industry. PolyMet's open pit mine and processing plant would operate for 20 years, but it would require decades, or even centuries, of expensive water treatment to protect the lakes and rivers that ultimately drain into Lake Superior.

Several Indian tribes and environmental groups also submitted their comments Thursday. They raised pointed questions on mercury contamination, how the state would protect future generations of taxpayers from what could be billions of dollars in water treatment costs, on the accuracy of critical data like how much water flows through the site and whether contingency plans exist for environmental disasters.

"We don't think that the [environmental review] demonstrates that the project is doable without adverse impacts," said John Coleman, environmental section leader for the Great Lakes Indian Fish and Wildlife Commission, which represents Great Lakes tribes. "The project started out data-poor and remains short on real data to support the conclusions."

The Minnesota Chamber of Commerce, the state's largest business lobbying group, said in its submission that the state's review had adequately addressed environmental concerns, and it urged the state to move forward with the next step in the regulatory review.

The Minnesota Department of Health also weighed in with more than 20 questions related to contamination of groundwater and drinking wells in the area. It recommended an increase in the number of monitoring wells to evaluate water quality in aquifers tapped for drinking. The plan also "minimizes" the potential for pollutants to seep into groundwater because it ignores evidence of fractured bedrock in the area, wrote Health Commissioner Dr. Edward Ehlinger.

Ehlinger also said mine discharges into the Partridge River could contaminate Colby Lake, which supplies drinking water for the town of Hoyt Lakes, and recommended that PolyMet participate in developing a contingency plan should Colby Lake become polluted.

The EPA's 16-page letter touched on some of the same issues raised by the Health Department, tribes and environmental groups, as well as additional impacts on moose, wild rice and long-term water monitoring. In all, it urged the DNR to address 37 issues in the final environmental impact statement, which the DNR must complete before the project can move to the permitting phase.

To complete the task, Colvin said, the company and the state may have to collect more data, and perhaps rerun some of the complicated computer modeling. He said he could not predict how long it might take. • 612-673-7394 • 612-673-4213