Minnesota Department of Natural Resources Commissioner Tom Landwehr on Monday said he expects the agency’s work on the PolyMet draft environmental impact statement to be completed by “early spring.”

It’s the most specific deadline so far in the ongoing regulatory saga over what would be Minnesota’s first copper mining and processing operation.

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Landwehr made the comment at a gathering of Iron Range school and municipal officials with top officials of the Minnesota DNR, the Minnesota Pollution Control Agency and the Iron Range Resources and Rehabilitation Board.

“My goal is to have it out by early spring. But that requires us to have everything fall into place,” Landwehr said after the meeting. “It’s kind of a bad news, good news thing. It’s not done yet, but at least we’ve put a time certain on it. As certain as we can be at this point.”

Public hearings were held on the PolyMet proposal in January, and the public comment period closed in March. The state brought in extra help for what was called a “tsunami’’ of comments. The DNR and Pollution Control Agency are sharing an extra $1 million annually, as of July 1, to hire six to eight new staff members who will help process permit applications and permit renewals from the mining industry.

In all, Landwehr said the agency received about 58,000 comments. Among those, there were about 8,000 unique subjects or thoughts, he said, that regulators must respond to. The DNR, U.S. Forest Service and U.S. Army Corps of Engineers are reviewing, categorizing and analyzing the comments to determine how best to respond to the issues and concerns raised.

“We’ve got 45 people working on it, counting the consultants,” Landwehr said, adding that PolyMet has made several changes to its proposal to address several of the comments made. The changes aren’t enough to require anther a round of public input, Landwehr said, but are “definite improvements’’ to the proposal

If and when the environmental review is deemed adequate, PolyMet hopes to apply for state and federal permits - an estimated 21 are needed - to begin construction and mining. The company also must secure long-term financing from creditors to build out the mine.

PolyMet plans a $600 million open pit mine and processing center near Hoyt Lakes, employing 300 people for 20 years or more, mining and processing copper, nickel, platinum, palladium and possibly other valuable metals.

Supporters say the project can be done without long-term harm to the environment, providing an economic boost to the regional economy.

Critics say the long-term potential for acidic runoff from copper-bearing rock, and other potential water pollution problems, aren’t worth the relatively short-term jobs created. They say the boom-and-bust cyclical nature of the mining industry is not sustainable for the region.