https://apnews.com/79ecf4591fb8cbfcb1299bdb7b3abf79

MINNEAPOLIS (AP) — The Minnesota Supreme Court will hear arguments Wednesday on an attempt by environmental groups to cancel a key permit for a long-stalled copper-nickel mine.

Opponents of PolyMet Mining Corp.′s project say state regulators should have included “end-of-pipe” limits on discharges of mercury, sulfates and other pollutants in the water quality permit. They also say the state improperly tried to suppress the concerns of the federal Environmental Protection Agency. The Minnesota Pollution Control Agency and PolyMet counter that the permit meets the legal requirements and that the project won't violate clean water standards.