The adequacy of Minnesota's rules overseeing copper-nickel mining within the same watershed as the Boundary Waters Canoe Area Wilderness will get a fresh look.

Attorneys for the Minnesota Department of Natural Resources and environmental group Northeastern Minnesotans for Wilderness agreed on Wednesday to have the state agency review its 27-year-old copper-nickel mining rules to determine if it can actually protect the BWCAW from copper-nickel mining pollution in the Rainy River Watershed.

The agreement sets off a process that will include a public comment period and the ability for parties — including Northeastern Minnesotans for Wilderness and Twin Metals, which is seeking to build an underground copper-nickel mine, processing facility and tailings storage facility in that watershed — to challenge the DNR's conclusion, which would trigger a contested-case hearing. And depending on the administrative law judge's conclusion, it could also force the agency to make rule changes.

"This is a first step in the right direction," Campaign to Save the Boundary Waters, which is part of Northeastern Minnesotans for Wilderness, wrote on its website Wednesday. "The mining rules guide how sulfide-ore copper mines are sited, and we believe there should be no such mines in the BWCA watershed."

The move stems from a June lawsuit in State District Court in St. Paul in which Northeastern Minnesotans for Wilderness, under the Minnesota Environmental Rights Act, argued the state's rules were outdated and should be updated to ban copper-nickel mining in the Rainy River Watershed of Minnesota, a move that would effectively kill the proposed Twin Metals project.

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While the DNR agreed to the review, it made clear in a statement it stood by its rules.

"It is important to emphasize that DNR has not agreed there is credible evidence that the current rule needs to be changed or that the rule is in anyway inadequate to protect the BWCA," the agency said. "DNR determined that the best course of action in response to this lawsuit was to propose a reasonable, neutral and agency-led process for evaluating the plaintiff’s allegation."

But the rule review process would not go forward if the lawsuit is thrown out, which Twin Metals requested in October.

The company said in a statement that it filed a motion to dismiss the lawsuit "because we do not believe it is appropriately before the court."

"We submitted our comments on the agreement filed by the DNR, and they assured us today that they are under consideration," the company said. "(Twin Metals Minnesota) expects to participate in substantive discussions involving all parties, and we expect that the DNR will defend its own rules and follow the law and the science as this case moves forward."

While state law is written by the Minnesota Legislature, it's up to state agencies to write rules to implement those laws.

The rules currently require mining stay outside a quarter-mile buffer from the Boundary Waters' edge, but opponents of copper-nickel mining say potential acid drainage from the planned Twin Metals facility would easily enter Birch Lake, which flows into the BWCAW via the Kawishiwi River.

Minnesota's non-ferrous mining rules have only been used to approve one project: the PolyMet copper-nickel mine, which sits outside the Rainy River Watershed and in the St. Louis River Watershed that flows into Lake Superior. PolyMet is not up and running as it faces numerous legal challenges to its permits.

The DNR emphasized on Wednesday that the rule review will not hamper its separate review of Twin Metals' mine plan, submitted in December 2019.

The DNR is in the first phase of an environmental review of Twin Metals as the agency prepares the scoping environmental assessment worksheet and draft scoping decision — a process that could take years.

The project is also under a separate federal review.