The U.S. Forest Service has denied Minnesota's request for the research from an aborted federal study about the impacts of copper mining on the Superior National Forest and its Boundary Waters Canoe Area Wilderness.

Department of Natural Resources (DNR) Commissioner Sarah Strommen requested the unreleased research in a letter last month to Bob Lueckel, regional head of the Forest Service in Milwaukee. Her agency needs the research, she wrote, because it is in charge of doing an in-depth environmental review of the copper-nickel mine plan that Twin Metals Minnesota has submitted.

Lueckel responded that the Forest Service study was never completed, reviewed or formally approved and so it won't give Minnesota the information.

"Not only are the incomplete data and documents deliberative pre-decision materials, but also reliance on potentially irrelevant and unreviewed data and analyses will only hinder our collective efforts to develop a sound environmental analysis of the current proposal," Lueckel wrote in his letter, dated April 13.

DNR assistant commissioner Jess Richards, who provided a copy of the letter, called the situation "complex."

"The DNR has not yet determined how we will respond to the USFS letter nor any implications their response may have to our review of the Twin Metals proposal," Richards said in an interview.

The DNR is early in the process of scoping out what the environmental impact statement will cover. Twin Metals submitted its formal plan for a $1 billion copper-nickel mine just outside the Boundary Waters in December.

The U.S. Forest Service and its umbrella agency, the U.S. Department of Agriculture, have defied multiple demands to release the study and its backup materials, including a request from U.S. Rep. Betty McCollum, D-Minn., chairwoman of a key funding subcommittee. It released 60 blacked-out pages to the Wilderness Society only after that organization sued.

The Forest Service study was nixed in Sept. 2018 after nearly two years of work. The USDA said the analysis didn't reveal anything new and was a "roadblock" to minerals exploration in the Rainy River Watershed.

That was shortly after the Trump administration reinstated two Twin Metals mineral leases, resurrecting the copper-mine project after the Obama administration refused to renew the leases because of the project's risk to the Boundary Waters.

A federal judge has upheld the Trump administration's decision to reinstate the leases.

Alison Flint, senior legal director for the Wilderness Society, called the Forest Service's denial disappointing but not "surprising."

"The Trump administration has gone to extreme ends to bury the canceled withdrawal study and keep its findings from the public," Flint said.

"As for the rationale that a publicly funded, science-based environmental assessment that was yanked at the 11th hour is somehow privileged, we will battle that one out in court," she said. "The public, the state of Minnesota, Congress, and other decisionmakers must have access to the information that was prepared with taxpayer dollars by dedicated resource experts at the Forest Service."

In an e-mail response, McCollum declared that the Forest Service report "will clearly demonstrate that sulfide-ore copper mining in the Superior National Forest will destroy the Boundary Waters Canoe Area Wilderness."

"The Minnesota DNR should not spend even one dollar of state taxpayer funds reviewing the Twin Metals project until this report is made public," she said.

Tom Landwehr, executive director of the Campaign to Save the Boundary Waters, called the Forest Service response "extremely disappointing."

"Is this the right place for a mine at all? That's what that document was intending to answer," Landwehr said. "Without that information we are jumping to the middle of the board game ignoring the first critical steps."