Critics of a proposed copper-nickel mine in northern Minnesota are urging people who oppose the project to make their voices heard as the public comment period opens on the final environmental review for the mine.

Groups opposed to the proposed said at a news conference Friday they would like to match the 58,000 comments submitted on the previous version of the document. But they say the narrow 30-day window makes that hard.

The Department of Natural Resources released the massive document last Friday. DNR Commissioner Tom Landwehr says he expects to certify it as adequate around February, which would let PolyMet apply for permits.

PolyMet says the review shows that the mine can operate safely in compliance with environmental laws while creating hundreds of high-paying jobs in a region that badly needs them.