President Joe Biden's administration is seeking a 20-year moratorium on mining in Superior National Forest near the Boundary Waters Canoe Area Wilderness, restarting a process that started, and stopped, under previous administrations.

The U.S. Department of Interior and U.S. Department of Agriculture — which together regulate mining — said in a joint statement Wednesday that they want to protect Minnesota's Boundary Waters, which they called a "unique natural wonder."

The Forest Service has applied to the Bureau of Land Management for a 20-year mineral withdrawal of more than 200,000 acres of federal land in the greater watershed that includes the Boundary Waters. Such a withdrawal of land puts a moratorium on new mining permits and leases. Only Congress can enact a permanent ban.

As part of the action, the Forest Service will restart a previously canceled study of the environmental, cultural and economic impacts of mining near the Boundary Waters.

Notice of the withdrawal request is to be posted in the Federal Register shortly, triggering a 90-day public comment period. A final decision could take two years.

It is unclear what impact the withdrawal process or moratorium would have on the $1.7 billion Twin Metals copper-nickel mine that Chilean copper king Antofagasta wants to build next to the Boundary Waters. The project has union support, but the hardrock mine is vehemently opposed by environmental groups who say it will pollute the area's pristine water with toxic sulfide.

The company already holds two crucial federal mineral leases that were renewed under the Trump administration after being canceled by the Obama administration.

The Interior Department confirmed Wednesday that a proposed mineral withdrawal does not affect existing leases.

It could, however, affect a possible third mining lease that Twin Metals has indicated it wants. That matter is tied up with the federal environmental impact statement on the mine plan.

Meanwhile, the reinstatement and renewal of Twin Metals' two minerals leases remains in litigation and under federal review. If the leases are found to be invalid, it could block the Twin Metals project. There is no deadline for the federal review of the lease decisions, the Interior Department said Wednesday.

As for seeking the mining moratorium, the interior and agriculture agencies said they were reacting to "broad concerns about potential impacts of mining on the wilderness area's watershed, fish and wildlife, Tribal trust and treaty rights, and the nearly $100 million annual local recreation economy."

"A place like the Boundary Waters should be enjoyed by and protected for everyone, not only today but for future generations," Secretary of the Interior Deb Haaland said in the statement.

Agriculture Secretary Tom Vilsack called the boreal outback "irreplaceable."

"I have asked the Forest Service to work with the Bureau of Land Management to complete a careful environmental analysis and engage the public on whether future mining should be authorized on any federal land adjacent to this spectacular and unique wilderness resource," Vilsack said.

Vilsack, agriculture secretary during the Obama administration, first initiated the mineral withdrawal in late 2016, and the Forest Service undertook a major environmental review of mining in Superior National Forest.

The Trump administration then canceled that study as it approved the Twin Metals project. And the administration refused to make the unfinished study public despite an onslaught of demands and court actions to do so. Like other organizations, the Star Tribune received a version consisting of 60 blacked-out pages of redactions.

Antofagasta subsidiary Twin Metals Minnesota has been developing plans for a $1.7 billion underground copper-nickel mine along Birch Lake, just outside the Boundary Waters, to open by 2030.

It is the second of two copper-nickel mines proposed for Minnesota, which would be the state's first-ever hard rock mines. The other project is the PolyMet copper-nickel mine further south in Babbitt and Hoyt Lakes, which is tied up in permit disputes.

Twin Metals, and labor unions in line for new members from the jobs created by the project, decried the move as unnecessary and shortsighted. In a statement Twin Metals said it's "deeply disappointed" and determining the best path forward.

"We are firmly dedicated to the communities of northeast Minnesota and to advancing a sustainable mining project that will bring much-needed economic growth to our region, in addition to the opportunity to responsibly develop the critical minerals needed for our global efforts in combating the climate crisis," Twin Metals spokeswoman Kathy Graul said in a statement.

Two unions with agreements to build the Twin Metals mine called the decision "counterproductive." The U.S. needs to lessen dependence on foreign countries for metals crucial to the energy transition away from fossil fuels, they said.

"This move will send a message to the mining industry that they shouldn't bother looking at the United States to produce those metals," said Jason George, business manager of the International Union of Operating Engineers Local 49. "That is a massive missed opportunity for job creation, and leaves us fully dependent on unstable nations to supply the metals we need to combat climate change."

In an interview, U.S. Rep. Pete Stauber, an Iron Range Republican, called the decision a "political stunt" to ban mining in northeast Minnesota that will "kill thousands of jobs."

Environmental groups called the announcement a major win. Chris Knopf, executive director of Friends of the Boundary Waters, and Becky Rom, national chair of the Campaign to Save the Boundary Waters, both called the action a huge step toward permanently protecting the pristine boreal area.

"The appropriate next step for the administration is to revoke the two Twin Metals leases that the Trump administration unlawfully reinstated," Rom said. "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."

U.S. Rep. Betty McCollum, a St. Paul Democrat and mine opponent, said she welcomed the return to science-based decisionmaking regarding public lands.

"After years of broken promises and ongoing obstruction of taxpayer-funded data from the prior administration, I am pleased that President Biden is committed to completing the necessary analysis to understand the impacts that sulfide-ore mining could have on this priceless reserve of fresh water, the biodiverse habitat it supports, and the economic livelihood of the surrounding community," she said in a statement.

Mining on federal lands is regulated by both Interior's Bureau of Land Management, which governs the underground minerals, and by Agriculture's Forest Service, which controls surface land.