In March 2019, the U.S. Army Corps (“Corps”) issued a Clean Water Act, Section 404 (“CWA”) permit to PolyMet Mining Inc. (“PolyMet”) for an open-pit copper-nickel mine in Minnesota.

CWA, Section 404, requires Corps authorization before any work involving placement of fill or discharge of dredged materials begins in any waters of the United States (“WOTUS”). Prior to obtaining the Section 404 permit, PolyMet must have obtained a Section 401 state water quality certification. Section 401 of the CWA requires that an applicant, who is applying for a Section 404 permit and whose conduct that may result in a discharge of pollutants into the WOTUS obtain a state water quality certification ensuring compliance with all applicable water quality standards, limitations, and restrictions. Section 401 of the CWA, provides authority to states and authorized tribes to protect the water quality of federally regulated waters within their borders, in collaboration with federal agencies, such as the Corps. Accordingly, the Corps in this case acknowledged “that [the] EPA and the Band have CWA authority on water quality matters concerning the [Tribe’s] Reservation.”

On August 3, 2021, the Fond du Lac Band of the Lake Superior Chippewa (“Band”) submitted its “will affect” determination, objection letter, and a hearing request to the U.S. Environmental Protection Agency (“EPA”) and the Corps, following the EPA’s “may affect” determination. The Band’s determination, objection letter, and hearing request came after the Band’s adoption of newly adopted numeric water quality standard for specific conductance to protect sensitive macroinvertebrate species and the relatively high biodiversity in the Band’s waters. The Band claimed and the EPA supported, that the proposed mine would result in mercury contamination to nearly 6,000 acres of wetlands, as well as fragmentation impacts to approximately 939 acres.

On May 3-5, 2022, the Corps held a public hearing, where the Corps heard and received information from the EPA, Band, PolyMet, and over 22,500 public comments. As a result of the hearing, the Corps revoked PolyMet’s suspended CWA, Section 404 permit. The Corps reasoned that it could not “reissue or modify the suspended permit” due to “the absence of any necessary permit conditions to ensure compliance with the applicable downstream water quality requirements of the Band as required by CWA Section 401(a)(2).”

Despite the fact that PolyMet’s CWA, Section 404 permit and Minnesota CWA, Section 401 certification predated the Band’s adopted numeric water quality standard for specific conductance, the EPA determined that the Section 404 permit would authorize activities that would contribute to St. Louis River’s already exceeding numeric water quality criterion. The EPA concluded that “even relatively small increases in specific conductance loadings and/or decreases in dilution capacity would result in violations of the Band’s water quality requirements.” Thus, the Corps revoked PolyMet’s permit, allowing PolyMet to submit a new CWA, Section permit application, so long as it meets the applicable water quality requirements for its project, which are always subject to change.