PolyMet Water Pollution Permit

What is the water pollution permit?

Under Minnesota law, PolyMet’s discharge of pollution either to surface waters (wetlands, streams, rivers, lakes) or to underground waters requires a State Disposal System (SDS) permit.

Under federal law, PolyMet’s discharge of pollution into surface waters either directly or through groundwater must be regulated under the Clean Water Act. An April 2020 U.S. Supreme Court decision confirmed that the Clean Water Act covers discharge through groundwater to surface waters that is the “functional equivalent of a direct discharge.” The permit required under federal law is called a National Pollutant Discharge Elimination System (NPDES) permit.

Since the NPDES portion of the permit must comply with the Clean Water Act, the U.S. Environmental Protection Agency (EPA) typically comments on important draft NPDES permits, like the PolyMet permit, in order to advise Minnesota regulators whether the permit complied with federal legal requirements.

The St. Louis River near Carlton, Minnesota. Photo by WaterLegacy.

What’s the current status?

The Minnesota Pollution Control Agency (MPCA) issued a combined NPDES/SDS permit for PolyMet water pollution on December 20, 2018 and simultaneously denied requests by WaterLegacy and our allies for contested case hearings. WaterLegacy appealed from MPCA’s permit decision on January 22, 2019.

On May 17, 2019, WaterLegacy asked the Minnesota Court of Appeals to transfer the MPCA PolyMet appeals to district court due to evidence that MPCA’s PolyMet permit process was improper and that EPA’s comments on the PolyMet water pollution permit had been suppressed. The Minnesota Court of Appeals granted WaterLegacy’s motion and issued a June 25, 2019 Order, transferring the case to district court to determine whether “irregularities in procedure” had occurred in MPCA’s issuance of the PolyMet water pollution permit.

For the first time in Minnesota history, a court found that a state decision – MPCA’s approval of the PolyMet water pollution permit – used “irregular procedures” hidden from the administrative record. But the District Court’s order on September 3, 2020 was too narrow. In November 2020, WaterLegacy and our allies appealed the order to the Court of Appeals, seeking broader agency accountability as well as reversal of MPCA’s weak and inadequate PolyMet water pollution permit.


The Minnesota Court of Appeals issued an Order on August 6, 2019 suspending the PolyMet water pollution permit. As a result, no construction can begin related to the PolyMet water pollution permit. WaterLegacy’s appeals from the MPCA water pollution permit and the narrowness of the District Court’s order finding procedural irregularities are consolidated for briefing and decision by the Minnesota Court of Appeals.

What’s the history of the water pollution permit?

MPCA proposed a draft NPDES/SDS water pollution permit for the PolyMet mine, plant and waste disposal facilities on January 31, 2018.

WaterLegacy opposed the MPCA’s PolyMet water pollution permit and requested a contested case hearing. On March 16, 2018, WaterLegacy submitted detailed technical comments and 77 exhibits, including expert opinions and publications. WaterLegacy’s comments included the following criticisms:

  • MPCA failed to set water quality-based effluent limits on direct surface discharge of PolyMet wastewater to wetlands, streams, and rivers at its tailings waste facility and processing plant.
  • MPCA failed to set enforceable limits to prevent PolyMet contaminated seepage through groundwater to nearly wetlands, streams and rivers from violating Minnesota water quality standards.
Watersheds and streams potentially affected by PolyMet discharge (from Final EIS).
  • The PolyMet mine would cause violations of Minnesota water quality standards for toxic metals, particularly mercury; for salts and ions toxic to fish; and for sulfate pollution upstream of wild rice waters.
  • MPCA monitoring would not disclose violations of water quality standards in wetlands near the pollution source; monitoring for sulfate is particularly inadequate.
  • MPCA failed to follow federal law protecting the Lake Superior watersheds of the Great Lakes from toxic metals pollution,
  • The combination of wetlands changes, sulfate pollution to the air and water, and mercury pollution to the air and water would increase mercury contamination of fish, violating both Minnesota water quality standards and the downstream water quality standards of the Fond du Lac Band of Lake Superior Chippewa.
Despite strong opposition, MPCA issued a PolyMet permit that lacked any water quality-based effluent limits. The permit also failed to regulate seepage from pollution collected at the mine and the tailings waste facility and discharged through groundwater to nearby surface waters. The PolyMet water pollution permit issued by MPCA was inadequate, unenforceable and violated the Clean Water Act. WaterLegacy appealed MPCA’s decision issuing the permit to the Minnesota Court of Appeals.

Learn about the Appeal and the status of the case.