A federal judge on Tuesday dismissed a challenge to the US Environmental Protection Agency’s (EPA’s) oversight of a water quality permit issued to PolyMet Mining, which is developing the NorthMet copper/nickel/palladium project in north-eastern Minnesota.

The challenge, filed in September 2019 by the Fond du Lac Band of Lake Superior Chippewa in US district court in Minneapolis, had argued that the EPA should have objected to PolyMet’s permit before it was issued.

However, Judge Patrick Schiltz held that it had no jurisdiction to review EPA’s oversight role, and so dismissed the Band’s claim.

The decision ended the only federal court challenge to PolyMet’s water quality permit.

PolyMet continues to litigate that permit in the Minnesota Court of Appeals, in part to defend a favourable Ramsey County District Court decision last fall finding that the permit was not the result of procedural irregularities.

Further, the federal court separately allowed the Band to proceed with claims that the EPA should have notified the Band about the PolyMet project’s potential to affect Band’s reservation, which lies 112 km downstream.

The Minnesota Pollution Control Agency has said that the project will have no effect that far downstream, PolyMet noted.

When operational, NorthMet will become one of the leading producers of nickel, palladium and cobalt in the US, which is increasingly searching for locally mined sources of critical and minerals.

Located within Minnesota’s Mesabi Iron Range, the NorthMet project has a measured and indicated resource of 649-million tonnes. PolyMet plans to develop the mining operation in two phases, the first of which involves development of 225-million tons – nearly one-third of NorthMet’s known resource – into an operating mine processing 32 000 t/d over a 20-year mine life. It also includes rehabilitating the former LTV Steel Mining Company processing plant.

Phase 2 involves construction and operation of a hydrometallurgical plant to treat nickel sulphide concentrates into upgraded nickel/cobalt hydroxide and recover additional copper and platinum-group metals.