Minnesota Supreme Court orders new hearing in PolyMet mine dispute

The Minnesota Supreme Court gave a victory to environmentalists Wednesday in the long-running battle over the proposed PolyMet copper-nickel mine in northeastern Minnesota, sending the dispute back to the state Department of Natural Resources for further proceedings on whether the mine’s waste pond would effectively keep pollution contained.

The Supreme Court also affirmed a 2020 decision by the Minnesota Court of Appeals to reverse the DNR’s decision to grant PolyMet a critical "permit to mine" because the state agency failed to set a fixed term for the permit. It ordered the DNR to set an appropriate term.

The justices held that the DNR must conduct a trial-like proceeding known as a "contested case hearing" to gather more information on whether the planned bentonite clay lining for the waste basin will work as intended. That’s narrower than what project opponents had hoped for, though they quickly declared a win.

The state’s highest court said the appeals court erred in 2020 when it sent the case back to the DNR for a contested case hearing on the broader impacts of the project. The justices said the DNR did not abuse its discretion in declining to hold a contested case hearing covering other issues because the agency had "substantial evidence" to support its conclusions.

The Supreme Court also said the appeals court erred when it reversed two dam safety permits for the project.