An outfitter from Ely, Minn., a young cancer survivor and a bipartisan group of U.S. House members led by Rep. Betty McCollum, D-Minn., made eloquent arguments Wednesday in favor of a bill that would impose a federal ban on copper mining, an industry notorious for water pollution, in the watershed of the fragile Boundary Waters Canoe Area Wilderness (BWCA).

But fodder for the most compelling argument on the bill’s behalf came from a surprising source: Frank Ongaro, executive director of the industry group Mining Minnesota. Ongaro has long been an aggressive advocate for the Twin Metals Minnesota copper-nickel mine proposed not just in the BWCA’s watershed but within a few miles of the wilderness itself.

In an exchange with an editorial writer this week, Ongaro’s ire was focused less on the bill’s potential threat to Twin Metals and far more on how it could deter other firms that want to mine in the BWCA watershed. There are “at least two” other companies that are “investing tens and tens of millions of dollars in proving up their resources” and “are very serious,’’ he said, adding that one of them has a “large deposit” that straddles both the BWCA and Lake Superior watersheds.

It’s certainly no surprise that mining companies covet the geologic riches embedded in northeastern Minnesota’s ancient rocks, some of the richest deposits of precious metals in the world. But what Ongaro’s comments make clear is that there are multiple firms seriously pursuing projects, with more likely to follow.

McCollum’s bill isn’t just about trying to stop or limit Twin Metals. Instead, the legislation is desperately needed to prevent the federal forest lands in the BWCA’s watershed from becoming a mining industrial district.

Hard-rock copper mining has a sordid history. Its legacy includes acid runoff and heavy metal spills into nearby waterways. One of its waste storage systems can also produce something called “fugitive dust” — containing potentially reactive materials like sulfur — that can spread over nearby lakes, forests or communities.

Northern Minnesota has one of the world’s most extreme climates, and the risk of a mistake, even with modern technology, that could permanently pollute the BWCA is simply too great to allow one mine, much less multiple mines, to operate near the wilderness. These among the reasons the Star Tribune Editorial Board made its case opposing the Twin Metals mine in a Nov. 24 editorial, “Not this mine. Not this location.”

It’s important to note that McCollum’s bill would not affect PolyMet, another northeastern Minnesota copper-nickel mine situated outside the BWCA watershed. Instead, the bill would permanently ban sulfide-ore copper mining on about 234,000 acres of federal forest land that lie inside of it.

The mining industry’s standard response to efforts like McCollum’s frequently boils down to favoring letting the regulatory process play out and seeing if the project can meet environmental standards. This disingenuously ignores the accumulating evidence that the process isn’t trustworthy at the state or federal level.

Last summer, the Star Tribune revealed that a Minnesota agency staffer worked to keep federal regulators’ concerns about PolyMet out of the written record. On Monday, a state Court of Appeals rejected three permits PolyMet had obtained from the state, essentially rapping regulators for a lack of transparency. At the federal level, the Editorial Board has long criticized the Trump administration for aborting a study of copper mining’s risks to the BWCA. The information gathered 20 months into a 24-month study still has not been released.

The New York Times also recently chronicled the Trump administration’s efforts to weaken the National Environmental Policy Act (NEPA) and other regulations safeguarding air and water quality. “These mining companies say they want to follow all the laws, but I certainly haven’t heard them complaining about weakening NEPA or gutting the Clean Water Act,” said Jason Zabokrtsky, who owns Ely Outfitting Company.

It is a shame that Minnesota’s U.S. senators don’t share the urgency of McCollum or business owners such as Zabokrtsky. At this point, McCollum’s ban has no companion bill in the Senate. That’s a big problem when home-state senators are expected to lead on bills like this. A spokeswoman for Sen. Tina Smith, a Democrat, said she won’t be introducing a companion bill or co-sponsoring one at this point.

Minnesota’s senior senator, Democrat Amy Klobuchar, didn’t respond to inquiries from an editorial writer. Her leadership on this politically dicey issue is vital. Her failure to respond reflects poorly on a presidential candidate who will face far tougher calls should she win the White House.