The federal government’s sudden decision to reopen mineral exploration just outside the Boundary Waters Canoe Area Wilderness was a resounding defeat for wilderness advocates.

But for the mining industry, it means back to business as usual.

By 2016, when the U.S. Forest Service adopted the temporary ban on exploratory drilling, mining companies had already poked thousands of holes in the ground in northern Minnesota in a decadeslong hunt for copper, nickel, platinum and other precious metals. Now, the grinding sound of the drill rigs in 234,000 acres of the Superior National Forest around Ely will resume and, over the next few years, probably increase, say those in the industry.

More importantly, the decision to lift the ban makes it more likely that at some point all that exploration will result in a mine.

Mining companies “are not doing this because they are interested in revitalizing the region,” said Jeremy Drucker, communications director for Save the Boundary Waters an advocacy group fighting for the long-term mining ban near the BWCA. “Any exploration is being done for the sake of turning a profit for someone.”

The BWCA, a 1 million-acre federally protected wilderness, has what its advocates say is the misfortune to be next to one of the largest untapped deposits of precious metals in the world. Geologists have known about it for 60 years, and mining companies have been measuring the concentrations and locations of the deposits for almost as long. Even during the two-year moratorium that ended Thursday, exploration has continued outside the 234,000 acres in question on federal lands, as well as on state and private lands inside.

But those particular acres that were covered by the stay on exploration, primarily south of the BWCA, hold some of the richest mineral deposits in the state — an estimated $500 billion worth.

The first potential mine in the area, which had been stalled by the restrictions on exploration, belongs to Twin Metals Minnesota. A subsidiary of the Chilean giant Antofagasta, Twin Metals had its mining leases reinstated by the Trump administration in 2017. It’s back at work developing a $2.8 billion underground mine a quarter-mile from the edge of the BWCA along the Kawishiwi River that feeds into it. It also lies in the headwaters of the Rainy River that flows to Voyageurs National Park and Rainy Lake.

Wilderness advocacy groups led a successful effort in 2016 to persuade the U.S. Forest Service under President Barack Obama to adopt a two-year ban on exploration while it conducted an in-depth environmental, economic and cultural analysis to determine if such mining was too much of an environmental risk so close to the wilderness. If so, the ban would have been extended to 20 years.

Then, the Forest Service expressed serious concerns about the potential ramifications. Hard rock mining carries much greater risks than taconite mining because the waste can produce an acid when exposed to air and water that leaches toxic heavy metals from rock. If it contaminates the lakes and streams in the water-rich area of northern Minnesota, it could cause significant damage to aquatic life.

Mining companies say their projects can be built with minimal environmental risks.

But last week U.S. Agriculture Secretary Sonny Perdue, who oversees the Forest Service, abruptly suspended the environmental review, saying the agency had not uncovered any new information.

Instead, the Bureau of Land Management and the U.S. Forest Service will resume granting permits for prospecting on federal lands, he said.

The state also holds 147,000 acres of mineral-rich land in the same area that was under consideration for protection, but it was not immediately clear whether those, too, will be available for additional exploration.

At the time the ban was implemented, Gov. Mark Dayton expressed serious misgivings about the risks to the wilderness from mining. But later he endorsed the $1 billion open pit project by PolyMet Mining Corp. near Hoyt Lakes that is outside the area covered by the moratorium. That mine would drain to the St. Louis River and Lake Superior.

Initially at least, not much will change, said those in the industry. Officials from two mining companies that are exploring for minerals in Minnesota, Teck and Kennecott Exploration Co., said they have no plans to expand their exploration.

Harry Noyes, president of Atlanta-based Encampment Minerals, which is actively exploring around the region in question with state and federal permits, declined to discuss his company’s plans. But it does have state and federal leases in the area south of the BWCA, he said.

Applying for a prospecting lease is not something mining companies do lightly, he said, because they come with significant costs and obligations.

“Any prospecting permit sets up a series of requirements,” he said. Companies must diligently pursue exploration and make a mineral find within two years — a financial commitment, he said. If they don’t, they have to explain why to the federal agencies before they can get an extension, which lasts only four years.

A similar process holds for state leases, said Frank Ongaro, executive director of Mining Minnesota, a trade group. The state puts lands for prospecting up for bid annually and sells leases to the highest bidder. The companies must provide a work plan, and the leases’ cost go up over time, he said.

“Eighty or 90 percent of the leases are returned back to the state within 10 years,” he said.

But eventually, if a company finds enough minerals to warrant a harder look, it applies for more permanent leases, he said. That could be followed by a feasibility study, which Twin Metals has already completed, and eventually a mining plan and request to the state and federal governments for permits to mine.

PolyMet is the only company in the state to ask for a copper-nickel mining permit — a process that has taken 10 years and still isn’t over. It’s waiting for a decision by the state on its permit.

For now, Ongaro said, the most significant consequence is that the chilling effect the ban had on the industry is gone. As a result, new companies from around the globe might start looking around, and the ones already in the state will poke more holes in the ground.

“At least,” he said. “I hope so.”