The Trump administration has cleared the way for renewed mineral leasing — and potentially mining — in about 365 square miles of the Superior National Forest within the watershed of the Boundary Waters Canoe Area Wilderness.

On Thursday, the U.S. Department of Agriculture canceled a study on the potential environmental impact of mining in the region, putting an end to the proposed Obama-era ban on mining and exploration there.

The U.S. Forest Service had launched the study after the Obama administration proposed a "mineral withdrawal" — a 20-year mining ban — in the area during its waning days in December 2016, based on concerns that mining activities in the Boundary Waters watershed "could lead to irreversible impacts upon natural resources," and result in "perpetual treatment of water discharge" at future mines.

Thursday's announcement won't open up the Boundary Waters Canoe Area Wilderness to mineral exploration. But the 365 square miles in question are adjacent to the BWCAW and within its watershed.

In a statement announcing the decision, U.S. Agriculture Secretary Sonny Perdue said after 15 months of review, that analysis did not reveal any new scientific information.

The USDA can both "protect the integrity of the watershed and contribute to economic growth and stronger communities," he said.

The announcement marked the Trump administration's second major reversal of decisions made on mining in the Superior National Forest. Earlier this year, the Interior Department reinstated two mineral leases that the Twin Metals mining company had attempted to renew in 2016, as it pursues plans for an underground copper-nickel mine near the Kawishiwi River outside Ely, Minn.

The Obama administration had denied Twin Metals' requests to renew its mineral leases, which gave the company the rights to pursue exploratory drilling in the area, and potentially open a mine, when it announced the mining moratorium. Environmental groups have since challenged the reversal of the lease decision in federal court.

Untapped mineral deposits

A ban on mining has been lifted around the Boundary Waters Canoe Area Wilderness in the Superior National Forest. William Lager | MPR News

The area of the Superior National Forest that hangs along the southern edge of the Boundary Waters is home to the Duluth Complex, believed to be one of the richest untapped deposits of copper, nickel and precious metals in the world.

Mining companies have been exploring the region for decades, although no copper-nickel mine has yet opened.

PolyMet Mining is on the doorstep of opening the state's first copper-nickel mine. The Minnesota Department of Natural Resources has released a draft permit to mine for the project, and could decide as soon as this fall whether to approve the project.

But that mine wasn't subject to the proposed moratorium, because it's located outside the Boundary Waters watershed, near Babbitt.

The Twin Metals proposal is next — and other companies are also exploring in the region.

Competing visions for the future of northern Minnesota

The reopening of mining possibilities elevates the debate between two competing visions for the economic future of northeastern Minnesota.

One would create, essentially, a new branch of the Iron Range: It hinges on the creation of a new, potential copper-nickel mining region that could create hundreds — if not thousands — of direct, high-paying jobs, and the spinoff economic activity that accompanies them.

Supporters argue that together, those mines, if developed, could transform northeastern Minnesota's economy.

"This action upholds what Minnesotans who believe that a mining economy can coexist with a treasured environment have been saying for nearly two years," said Nancy Norr, chair of Jobs for Minnesotans, an advocacy group. "This is a significant win for our way of life in Minnesota."

The Twin Cities-based Center of the American Experiment released one of two studies on the potential economic impact of copper-nickel mining in northeastern Minnesota last month. It forecasts that the copper mining industry could inject $3.7 billion annually into the state's economy.

A second study, from Harvard economist James Stock, predicts that the boom-and-bust nature of a new mining economy would have a negative effect on the region's growing outdoor recreation-based economy.

That study supports the other vision for the region's future: An economy based on outdoor recreation and the natural amenities of northeastern Minnesota that draw tourists and retirees and people who want to move to a place like Ely because of its access to the pristine wilderness of the Boundary Waters.

"This decision will hurt the thousands of people whose livelihoods and economic well-being has been built on a thriving outdoor recreation economy in the region," the Friends of the Boundary Waters Wilderness said in a statement Thursday.

Broken promises or a righting of wrongs?

Environmental groups have accused the U.S. Department of Agriculture, which houses the U.S. Forest Service, of not finishing the environmental study it had promised to complete.

"The Trump administration broke its word to us, to Congress, and to the American people when it said it would finish the environmental assessment and base decisions on facts and science," said Alex Falconer, Executive Director of the Campaign to Save the Boundary Waters.

After it put in place its moratorium, the USDA expected to study the proposal for two years, then send its findings to the federal Interior secretary, who would then base his or her decision on the findings.

The group said the Trump administration did not complete the full study of the proposed mineral withdrawal, something Perdue had earlier promised to Congress.

Other mining critics accused the administration of caving to a foreign-owned corporation. Twin Metals Minnesota is a subsidiary of Santiago, Chile-based Antofagasta.

Twin Metals said it supported the administration's decision.

"This important action ensures that federal lands that have been open to responsible mining activity for decades will remain open," said CEO Kelly Osborne.

Mining advocates argued the proposed mining moratorium was unnecessary and redundant, since mining projects already have to go through an extensive environmental review process before they're approved.