Correction (Jan. 26, 2018): An earlier version of this story inaccurately identified the company behind this mine proposal. It also included an erroneous photo, which has been removed. The below copy has been updated.
The U.S. Forest Service says it's downgrading an environmental review of a proposal to withdraw certain national forest land in Minnesota from minerals exploration for up to 20 years.
The land includes the site where Twin Metals wants to mine for copper and nickel, near the Boundary Waters Canoe Area Wilderness.
Supporters of the project have touted the jobs it would bring, but opponents fear the mining could lead to sulfuric acid polluting the area's pristine waters.
The Forest Service says it will do an environmental assessment rather than a more rigorous environmental impact statement, because no significant environmental impacts have been identified during a long public scoping period.
The Campaign to Save the Boundary Waters said the change means less opportunity for public input and rigorous scientific analysis.