Newfound Lake in the Boundary Waters Canoe Area Wilderness. A 93-page report by the U.S. Forest Service details the risks of mining near this area. (Bob King for Star Tribune Opinion/The Minnesota Star Tribune)

Opinion editor's note: Editorials represent the opinions of the Star Tribune Editorial Board, which operates independently from the newsroom.

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It's now abundantly clear why the Trump administration halted, then kept secret, an environmental assessment of copper mining's risks to Minnesota's Boundary Waters Canoe Area Wilderness (BWCA) watershed.

Neither President Donald Trump nor the industry lackeys he put in charge of the nation's natural resources wanted the public to see what was in it. They were all in on allowing a Chilean billionaire family to open the Twin Metals copper mine upstream of the BWCA.

But the report, which has finally been completed and a draft released, details the threat posed by mines like Twin Metals if operated outside the BWCA but within its fragile watershed.

The Star Tribune Editorial Board has long argued that there are places simply too risky to mine and that the BWCA watershed is one of them. The environmental assessment, which came out last month and summarizes numerous scientific research reports, strengthens this argument.

The report's findings should spur Minnesota's two increasingly influential U.S. senators — Amy Klobuchar and Tina Smith — to take action.

The Biden administration finished the report that the Trump administration halted and kept under wraps. It is also conscientiously moving to establish a 20-year moratorium on this type of mining on more than 225,000 acres in the BWCA watershed.

But permanent protection is needed to prevent a future administration from undoing those moves. A House bill introduced by Rep. Betty McCollum, D-Minn., would put permanent copper-mining protections in place for the BWCA. Unfortunately, it still lacks a Senate companion bill.

Klobuchar and Smith have previously said they were awaiting completion of the federal study before taking further steps. That report is out now, and the science is evident on the risks this type of mining poses.

Contacted this week, Smith provided a statement: "I firmly believe that we need to protect the Boundary Waters Canoe Area Wilderness. That's why I pushed for the completion of this study. Now that we have the scientific and economic analysis to understand the risks better, the findings deserve a thorough review. This is a top priority for me and I am carefully studying the report and considering next steps."

That's fine, but not enough. Klobuchar's office did not respond to a request for comment, which is frustrating given the broad support in her home state for protecting the BWCA from this type of mining. A 2020 Star Tribune poll found that "Statewide, 60% of registered Minnesota voters said they oppose building new mines near the federally protected wilderness, while 22% support it."

It's time to act. And it ought to be a Minnesotan who serves as the BWCA's Senate champion.

The U.S. Forest Service prepared the environmental assessment. The agency is involved because much of the land and mineral rights that mining firms seek to develop in this area are publicly owned and under federal oversight.

The 93-page report bolsters the need for a 20-year moratorium and permanent protections. Among its key findings:

The potential for "acid mine drainage and other water and air pollution."
The limitations of even "engineered mitigation technology" to prevent pollution, particularly long into the future.
The risks even if the mine is underground (as Twin Metals would be) because of surface activities, particularly the need for "permanent tailings or waste rock storage."
"Dry stack" waste storage, touted by mining proponents as an environmentally friendly alternative to traditional mine waste management, is not without its own pollution potential.

Twin Metals provided this statement: "Last week's action by the U.S. Forest Service is not informed by science and it attempts to inhibit the consideration of copper-nickel mining projects across a vast area of northeast Minnesota. It will affect the future domestic accessibility of clean energy minerals needed to combat climate change and strengthen U.S. supply chains."

Not informed by science? The Forest Service report summarizes the scientific research underpinning its findings. Citations are in the project documents and resource report files available online.

As for the domestic supply of critical minerals, the report also makes clear that whatever is mined in northern Minnesota would be sold globally, not reserved for U.S. use only. "Accordingly, there are no known effects to the United States' defense technologies or availability of minerals for renewable energy technologies attributable to the withdrawal application," the assessment concluded.

The report is solid and provides the details Minnesota's two U.S. senators need for next steps. We look forward to seeing them take action.

Editorial Board members are David Banks, Jill Burcum, Scott Gillespie, Denise Johnson, Patricia Lopez, John Rash and D.J. Tice. Star Tribune Opinion staff members Maggie Kelly and Elena Neuzil also contribute, and Star Tribune Publisher and CEO Michael J. Klingensmith serves as an adviser to the board.