"In due course." That's the imperious response from the Trump administration when asked again this week when it will release scientific information gathered during an aborted review of copper mining's impact on land adjacent to the beloved Boundary Waters Canoe Area Wilderness (BWCA).

A controversial May 15 federal decision to renew two mining leases blocked by former President Barack Obama's administration underscores the troubling questions about transparency raised by Rep. Betty McCollum, D-Minn., other members of Congress, and the Star Tribune Editorial Board. If the review, which was launched by the outgoing Obama administration and abruptly halted last fall by the Trump administration, actually supported that copper extraction can be done responsibly, why not release the science? The review was halted 20 months into a 24-month process.

The May 15 decision to renew the two mineral leases sought by the Chilean-­owned Twin Metals Minnesota sweeps away a significant hurdle the project faced. The proposed mine would not be in the BWCA, but would be in its watershed — putting the pristine waters at risk of acid runoff or other pollution. While Twin Metals still must undergo state permitting and likely remains years away from completion, the Trump administration's refusal to release the key data from the review creates doubts about whether politics, rather than science, cleared the path forward.

Even high-profile backers of the Twin Metals project, such as Minnesota Republican U.S. Reps. Tom Emmer and Pete Stauber, should recognize how the perception of secrecy jeopardizes public confidence in the entire approval process. That's not helpful for Twin Metals or other mining projects.

The administration's obstinance is even more alarming given McCollum's forceful advocacy and the "grave concerns" voiced in a May 1 letter by U.S. Forest Service retirees about pollution and other risks to the BWCA.

McCollum, who represents the state's Fourth District, has sent two strongly worded letters to the administration demanding review data. In congressional hearings, she's hammered Agriculture Secretary Sonny Perdue for breaking his 2017 promise to provide this information.

Yet the Trump administration continues to brazenly blow off its congressional-oversight obligations. And as its May 15 lease decision showed, it gave little heed to the remarkable letter signed by about three dozen Forest Service employees, the very people with the expertise to accurately assess mining's risks to the BWCA.

Clearly, McCollum needs stronger backup from her colleagues, particularly from Minnesota's delegation. It shouldn't have taken an editorial writer's inquiry to apparently prompt Democratic Sens. Amy Klobuchar and Tina Smith to send a letter on Thursday calling for the data's release. While the senators previously have weighed on other Twin Metals matters, Minnesotans would be well-served if Klobuchar and Smith became higher-profile advocates for transparency and joined McCollum in other protective efforts. For example, McCollum is pursuing legislative remedies to require completion of the halted study and commission a report from the independent National Academy of Sciences on Twin Metals' impact on the BWCA watershed.

In a statement provided to an editorial writer this week, Twin Metals said it has not yet submitted an official "Mine Plan of Operations" for agencies to review. Until then, it said, "speculation about the potential impacts to the area is premature and not based in fact or science."

Officials with the firm also said they support the right to request the documents but that "any production from the agencies must be in compliance with the law." Federal agency officials contacted by an editorial writer have not publicly cited legal barriers to releasing the data requested by McCollum.

In 2016, Thomas Tidwell, head of the Forest Service under Obama, warned of copper mining's potential to cause "serious and irreparable harm" to the BWCA. Were the head-spinningly swift steps from that stance to the Trump administration's industry-friendly policy based on science or something else? Data from the halted review is needed to answer that vital question.