The relative quiet in Minnesota in the days since state officials issued a draft permit for a new PolyMet copper-nickel mine near Babbitt and Hoyt Lakes has spoken volumes about the value of the 10-year regulatory path the project has trod.

State environmental regulators — reputed to be among the toughest in any state — laid out on Jan. 5 the contractual conditions under which they would give the project a green light. Those specifications were received with nary a ripple of complaint from PolyMet executives in Minnesota or Canada, where the firm has its headquarters.

“We believe we can meet all the permit conditions,” Brad Moore, PolyMet’s executive vice president of environmental and government affairs, told an editorial writer last week. “They protect Minnesota’s environment while giving us a chance to diversify the Iron Range’s economy, create jobs and show that we can do this here properly.”

Environmental watchdogs met the draft permit’s release with copious reminders of the water pollution risk associated with removing metals from sulfide-bearing ore, as copper-nickel mining requires. “No mine of this type has operated and closed without polluting local waters with acid-mine drainage,” warned Steve Morse of the Minnesota Environmental Partnership. “The long-term risks to the safety and health of downstream communities and Lake Superior far outweigh the short-term benefits.”

Those are stern warnings, based on a sorry history of sulfide mining elsewhere. But, notably, they stop short of challenging the legitimacy of the permitting process to which this project has been subjected, or the adequacy of the requirements contained in its draft mining permit. It’s the most important permission slip among more than 20 state and federal permits that PolyMet must secure before construction can begin.

Challenges may yet come. But to affect this project, they must come soon. The comment period allotted for the mining permit ends on March 6. Comments can be posted at or made in person at two public meetings that will consider several of the permits, Feb. 7 in Aurora and Feb. 8 in Duluth.

Any challenge will need to overcome the credibility that attaches to the data-driven scrutiny state and federal agencies have given PolyMet’s plan for the long-idled LTV taconite plant. Their work has been largely devoid of political meddling or procedural shortcuts. Regrettably, the same cannot be said for a second proposed copper-nickel mining venture, Twin Metals near Ely, which has seen interference by both the Obama and the Trump administrations — and, potentially, Congress — over federal mineral leases.

The fact that state agencies have been allowed to do their jobs on PolyMet — including taking the time to listen and respond to public input — sets a strong precedent that ought to apply to Twin Metals and any other future mining proposal. So does the state’s insistence on substantial “financial assurance” — akin to a damage deposit — before mining can begin. The state is pressing PolyMet for $75 million at the issuance of a mining permit, $588 million by year two and an annual review and adjustment thereafter. It’s likely that more than $1 billion in bankruptcy-proof financial assurance will be required of the company during the anticipated 20-year life of the project, earmarked to spare future state taxpayers should water issues arise long after mining ends. Such a requirement is a welcome first for a Minnesota mining operation.

PolyMet’s long permitting process has understandably tried the patience of Minnesotans eager to bring a new industry to the Iron Range. But it is precisely because sulfide mining is new to Minnesota that both state and PolyMet officials have been loath to take shortcuts. The PolyMet approval process will set the bar for future mining ventures in this state. So far, it appears that the bar will be high.