ST. PAUL, Minn. (AP) — The Biden administration moved Thursday to protect northeastern Minnesota’s pristine Boundary Waters Canoe Area Wilderness from future mining, dealing a potentially fatal blow to a copper-nickel project.

Interior Secretary Deb Haaland signed an order closing over 350 square miles (900 square kilometers) of the Superior National Forest, in the Rainy River Watershed around the town of Ely, to mineral and geothermal leasing for 20 years, the longest period the department can sequester the land without congressional approval.

The order is “subject to existing valid rights,” but the Biden administration contends that Twin Metals Minnesota lost its rights last year, when the department rescinded a Trump administration decision to reinstate federal mineral rights leases that were critical to the project. Twin Metals, which is owned by the Chilean mining giant Antofagasta, filed suit in August to try to reclaim those rights, and reaffirmed Tuesday that it’s not giving up despite its latest setback.

“Protecting a place like Boundary Waters is key to supporting the health of the watershed and its surrounding wildlife, upholding our Tribal trust and treaty responsibilities, and boosting the local recreation economy,” Haaland said in a statement. “With an eye toward protecting this special place for future generations, I have made this decision using the best available science and extensive public input.”

Critics of the project hailed the decision as a massive victory and called for permanent protections for the wilderness. But supporters of Twin Metals said the order runs counter to the administration’s stated goal of increasing domestic supplies of metals that are critical to the clean energy economy.

“The Boundary Waters is a paradise of woods and water. It is an ecological marvel, a world-class outdoor destination, and an economic engine for hundreds of businesses and many thousands of people,” Becky Rom, national chair of the Campaign to Save the Boundary Waters, said in a statement.

The proposed underground mine would be built southeast of Ely, near Birch Lake, which flows into the Boundary Waters. The project has been battered by shifting political winds. The Obama administration, in its final weeks, chose not to renew the two leases, which had dated back more than 50 years. The Trump administration reversed that decision and reinstated the leases. But the Biden administration canceled the leases last January after the U.S. Forest Service in October 2021 relaunched the review and public engagement process for the 20-year mining moratorium.

While the Biden administration last year committed itself to expanding domestic sources of critical minerals and metals needed for electric vehicles and renewable energy, it made clear Thursday that it considers Boundary Waters to be a unique area worthy of special protections. A day ago, the administration said it would reinstate restrictions on road-building and logging in the country’s largest national forest, the Tongass National Forest in Alaska.

Twin Metals said it was “deeply disappointed and stunned” over the moratorium.

“This region sits on top of one of the world’s largest deposits of critical minerals that are vital in meeting our nation’s goals to transition to a clean energy future, to create American jobs, to strengthen our national security and to bolster domestic supply chains,” the company said in a statement. “We believe our project plays a critical role in addressing all of these priorities, and we remain committed to enforcing Twin Metals’ rights.”

Twin Metals says it can mine safely without generating acid mine drainage that the Biden administration and environmentalists say makes the $1.7 billion project an unacceptable risk to the wilderness. Twin Metals says its design would limit the exposure of the sulfide-bearing ore to the effects of air and water. And it says the mine would create more than 750 high-wage mining jobs plus 1,500 spinoff jobs in the region.

Republican U.S. Rep. Pete Stauber, who represents northeastern Minnesota, condemned the decision as “an attack on our way of life” that will benefit only foreign suppliers such as China that have fewer labor and environmental protections. “America needs to develop our vast mineral wealth, right here at home, with high-wage, union protected jobs,” he said in a statement.

“Ultimately, this sends a chilling message to hardworking Minnesotans who need the widespread economic benefits of mining in our state and sends an even harsher message to the business community that they cannot expect fair treatment in Minnesota or the United States,” the Jobs for Minnesotans coalition of business and labor groups said in a statement.

While Democratic U.S. Rep. Betty McCollum, who represents the St. Paul area, applauded the order, she also warned in a statement that a future administration could reverse the decision.

The 1,700 square mile (4,400 square kilometer) Boundary Waters Canoe Area is the most-visited federally designated wilderness area in the U.S. It draws more than 150,000 visitors from around the world who paddle its more than 1,200 miles (1,900 kilometers) of canoe routes and over 1,100 lakes. According to the Interior Department, it contributes over $17 million annually to the outdoor recreation and tourism economy in northeastern Minnesota. Three Ojibwe tribes exercise treaty rights in the area covered by the moratorium.

The order does not affect two other proposed copper-nickel projects in northeastern Minnesota — the PolyMet mine near Babbitt and Hoyt Lakes and the Talon Metals mine near Tamarack — which lie in different watersheds.

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