The Biden administration on Wednesday canceled two federal minerals leases for the proposed Twin Metals copper-nickel mine in northern Minnesota, likely killing a project widely condemned for being too close to the pristine Boundary Waters Canoe Area Wilderness.

The huge underground mine would have tapped major reserves of copper and nickel — minerals key to a low-carbon economy — but also posed serious risks of contaminating the many waters surrounding it with sulfide and toxic heavy metals. Polls showed many Minnesotans did not support creating an industrial operation at a gateway to the federally protected wilderness.

The boreal outback covers more than 1 million acres, a maze of forested lakes, streams and wetlands where motorized boats are not allowed.

The U.S. Department of Interior issued its legal determination Wednesday. Two lawsuits challenging the legality of the minerals leases in Washington, D.C., courts will likely be dismissed. The two minerals leases were essential for Twin Metals, a subsidiary of Chilean copper mining giant Antofagasta, to develop the mine — its first major effort outside Chile.

"The Department of the Interior takes seriously our obligations to steward public lands and waters on behalf of all Americans. We must be consistent in how we apply lease terms to ensure that no lessee receives special treatment," Interior Secretary Deb Haaland said in a statement. "After careful legal review, we found the leases were improperly renewed in violation of applicable statutes and regulations, and we are taking action to cancel them."

The Minnesota Department of Natural Resources, which has been close to starting an environmental review of the mine, said it's reviewing the decision.

"Today's federal action raises significant questions about the feasibility of Twin Metals' project as proposed," the DNR said in a statement.

Twin Metals called the decision politically motivated and vowed to fight.

"The federal government's reversal of its position on the mineral leases that Twin Metals Minnesota and its predecessor companies have held for more than 50 years is disappointing, but not surprising given the series of actions the administration has taken to try and shut the door on copper-nickel mining in northeast Minnesota," the company said in a statement. "We will challenge this attempt to stop our project and defend our valid existing mineral rights. We expect to prevail."

Brian Hanson, chairman of Jobs for Minnesotans, a pro-mining coalition of business and labor groups, called the decision "disheartening" and an attack on northeast Minnesota.

"It doesn't make sense to make this kind of decision in the face of a country needing to deal with climate change and needing strategic minerals to do so," he said. "These are jobs. These are our livelihoods."

The question of opening Minnesota to hard-rock mining — mining for things other than iron ore — has opened deep divisions the state, a rift reflected in Minnesota's congressional delegation.

Republican Rep. Pete Stauber, a staunch mining advocate, accused President Joe Biden of playing politics with mining.

"We are not going to allow this administration or any other administration to stop mining in northeastern Minnesota," Stauber said. "It's a big part of our economy. It brings good-paying jobs for our families and the workforce here is second to none."

Elated environmental groups hailed the decision as victory for science, water and Iron Range communities.

Becky Rom, national chair of the Campaign to Save the Boundary Waters, called the decision "a return of the rule of law." The area's fragile ecosystem needs more permanent protections, she said. "We think it's time for Twin Metals to move on, go back to Chile."

Chris Knopf, head of the Friends of the Boundary Waters Wilderness, noted that the victory comes on the permit opener for entering the wilderness: "This is great victory on a day that everyone is getting their permits to celebrate the clean water and experiencing the wilderness."

Democrat Rep. Betty McCollum, a vocal opponent of the Twin Metals mine, issued a statement hailing the cancellation as a "a rejection of the deeply flawed and politically motivated process under the Trump administration and a victory for sound science and protecting a precious and irreplaceable natural resource."

Outfitters in Ely, an old mining town and jumping-off point for the Boundary Waters, were busily processing permit applications Wednesday when the Twin Metals news broke.

Jason Zabokrtsky, owner of the Ely Outfitting Company, said demand for Boundary Waters overnight permits skyrocketed after the U.S. Forest Service recently reduced the number available.

"It created what feels like a bit of a frenzy," he said.

He said the cancellation is great news but he hasn't had a moment to stop and think about it: "I have so many texts and e-mails and I haven't looked at any of them."

"I think the Boundary Waters is a real driver to our regional economy," he said. "A Twin Metals mine puts all of that at risk."

Ely itself is "generally just divided," Zabokrtsky said.

The copper-nickel mine Twin Metals wants to build would sit about 15 miles southeast of Ely, near Birch Lake and the South Kawishiwi River. The company is in the start of the regulatory process, but has been developing the plan for years and built a modern headquarters in Ely. It had hoped to have the mine running by 2030.

Its two hard rock mineral leases were first granted in 1966 to International Nickel Co., the predecessor of Twin Metals Minnesota. They come up for renewal every 10 years.

In 2016, under the Obama administration, the Forest Service determined it would not consent to renewing the leases because of the threat copper mining posed to the region. Twin Metals sued.

In 2018, under the Trump administration, the Twin Metals leases were reinstated. More litigation ensued.

The Biden administration signaled another change of course in October when it announced it's seeking a 20-year moratorium on mining on more than 200,000 acres of federal land near the Boundary Waters. The Forest Service is slated to finish its environmental analysis by June. Haaland will likely make the final call by the end of the year.

On the legislative front, McCollum has sponsored a bill to ban hard rock mining near the Boundary Waters. There's a companion bill at the state level, where there are other legislative efforts to restrict copper mining.

The DNR is reviewing the adequacy of Minnesota's rules for siting hard-rock mines.