Federal Approval: PolyMet Wetlands Destruction Permit 

What is the wetlands destruction permit?

Under the Clean Water Act, destruction of wetlands that are waters of the United States is prohibited unless the U.S. Army Corps of Engineers (Army Corps) grants a Section 404 permit to destroy (“dredge and fill”) wetlands. The proposed PolyMet mine would destroy and degrade wetlands, so a Section 404 permit was required for its proposed sulfide mine.

The U.S. Army Corps granted a Section 404 wetlands destruction permit to PolyMet on March 21, 2019. This federal permit allows PolyMet to directly destroy 933 acres of wetlands and requires that PolyMet buy another 162 acres of “credits” for wetlands destruction.

Under the Clean Water Act, a state where a project is located has the right to object to an Army Corps permit that could result in violation of state water quality standards or to approve the project. This is called Section 401 certification. The Minnesota Pollution Control Agency (MPCA) issued a (Section 401) certificate on December 20, 2018.

Section 401(a)(2) of the Clean Water Act also describes rights of “downstream states” – including tribes with “treatment as a state” to object to federal permits that would violate a downstream state’s water quality standards.

In 2016, in consultation with the Fond du Lac Band of Lake Superior Chippewa, WaterLegacy’s advocacy director wrote the first legal article advocating  for federal recognition of the authority of downstream tribes to object to federal permits. The U.S. Environmental Protection Agency (EPA) is required under the Clean Water Act to notify downstream tribes that discharge “may affect” their waters and give tribes the opportunity to call for a federal hearing to impose conditions on the permit to protect their waters.

Proposed PolyMet site wetland floor (2017). Photo by Robin Heil.

What’s the current status of the PolyMet wetlands destruction permit?

The Fond du Lac Band sued in federal court in 2019 opposing the PolyMet wetlands destruction permit. As of June 2021, the PolyMet wetlands destruction permit has been suspended. The reverse order timeline below explains recent developments.

June 6, 2022 – Army Corps Deadline for Public Comments on the Fond du Lac Band’s Objection.


May 3-5, 2022 –Army Corps Hearing on the Fond du Lac Band’s Objection.

Presentations from the Band and EPA, comments from PolyMet and the Band’s responses will take place on May 3-4. Verbal public comments are allowed on May 5.

Read Army Corps Notice of May 3-5, 2022 hearing.

August 3, 2021 – Fond du Lac Band “Will Affect Determination” and Objection

The Fond du Lac Band timely notified the Army Corps that the Band and its experts had determined that upstream PolyMet pollution “will affect the quality of the Band’s waters so as to violate the Band’s water quality requirements” on the Reservation. The Band cited violation of the Band’s strict numeric mercury standards and degradation of water quality as a result of specific conductance ionic pollution. The Band also notified the Army Corps of its objection to the PolyMet wetlands destruction permit under the Clean Water Act:

The Section 404 Permit issued by the U.S. Corps of Engineers should be revoked and not be issued because those violations of the Band’s water quality requirements violate Section 401(a)(2) of the CWA and Section 230.10(b) of the CWA regulations (aka the “404(b)(1) Guidelines”) governing issuance of Section 404 permits (40 C.F.R. Part 230).

June 4, 2021– EPA “May Affect Determination”

EPA determined that PolyMet discharge “may affect” the downstream Fond du Lac Band Reservation (and also waters of the State of Wisconsin). EPA’s decision started a process where the Band has 60 days to determine if PolyMet discharge “will affect” reservation waters, object to the permit, and obtain a hearing from the Army Corps, in which EPA will also make recommendations to insure compliance with downstream water quality standards.

EPA’s determination focused on mercury mobilization and methylation and relied on an updated opinion from Dr. Brian Branfireun that the PolyMet project would increase mercury in downstream tribal waters.

Read EPA’s Clean Water Act 401(a)(2) “May Affect” Determination (June 4, 2021)

Read Dr. Branfireun’s April 28, 2021 Opinion

Learn more on EPA’s web page on EPA’s PolyMet NorthMet Mine Clean Water Act 401(a)(2) Determination.

March 17, 2021 – PolyMet Wetlands Destruction Permit Suspended

Army Corps suspended its wetlands destruction permit on the basis that EPA is reviewing its Section 401(a)(2) “may affect” determination to consider downstream effects of PolyMet project so “it is therefore necessary in consideration of the public interest to suspend the 404 permit while the EPA reconsiders effects on downstream water quality from the proposal.”

Read U.S. Army Corps Letter to PolyMet Suspending Wetlands Permit (Mar. 17, 2021)

March 4-8, 2021 – Request for Remand of PolyMet Wetlands Destruction Permit

On March 4, 2021, the EPA asked the district court to allow a remand so that the EPA could consider and make a determination whether PolyMet discharge “may affect” Fond du Lac Band reservation waters. The court granted that motion on March 8.

The EPA also asked the Army Corps to suspend the PolyMet wetlands permit while the EPA made its evaluation.

Read EPA’s Letter to the Army Corps Requesting PolyMet Permit Suspension (Mar. 4, 2021)

February 16- 2021 – Court Preserves Band’s Section 401(a)(2) Claim

On February 16, 2021, the United States District Court for Minnesota denied a motion to dismiss and preserved the Fond du Lac Band’s Section 401(a)(2) claim that the EPA violated the Clean Water Act by failing to make a decision on whether PolyMet discharge authorized as a result of the federal wetlands permit “may affect” the Band’s downstream reservation waters.

The District Court ruled:

EPA had a legal duty to make a “may affect” decision—and given that EPA has admitted that it did not make such a decision—the Band would seem to have a plausible (perhaps even a slam‐dunk) claim that EPA did not act “in accordance with law.”

Read U.S District Court Decision Preserving Band’s Section 401(a)(2) Claim (Feb. 16, 2021)

September 10, 2019 – Complaint in Federal Court

On September 10, 2019, the Fond du Lac Band filed suit in the United States District Court for Minnesota against the Army Corps for issuing the wetlands permit and against the EPA for failing to exercise Clean Water Act oversight and failing to make the “may affect” determination that would trigger the Band’s rights to protect downstream reservation waters under Clean Water Act Section 401(a)(2).

Read Fond du Lac Band Complaint Against EPA and Army Corps (Sept. 10, 2019)

Reasons for opposition to the wetlands permit

Mercury Contamination

International mercury expert Brian Branfireun explained during environmental review that the PolyMet project would increase mercury in the water column and mercury contamination of fish.

Read Brian Branfireun’s expert report on the Final EIS

In response to Dr. Branfireun’s opinions and comments from WaterLegacy and the Fond du Lac Band, PolyMet provided MPCA with a new “analysis” denying that its proposed mine would increase mercury contamination of fish. In 2019, Dr. Branfireun submitted another expert opinion harshly criticizing both PolyMet’s analysis and MPCA’s reliance on it to certify the proposed PolyMet wetlands destruction permit.

In my opinion, PolyMet’s Cross-Media Analysis is a straw man . . . the weight of the scientific evidence indicates that the NorthMet project [ ] would create a substantial risk of ecologically significant increases in water column and fish methylmercury concentrations in downstream waters, including the St. Louis River due to changes in wetland biogeochemical processes (primarily mercury methylation) driven by hydrological impacts of pit dewatering, subsequent changes to wetland biogeochemistry as a function of these changes, and aqueous sulfate discharges to headwaters.

Read Brian Branfireun, Expert Opinion on Section 401 Certification for PolyMet Project (Jan. 20, 2019)

Wetlands Destruction

In the PolyMet Final EIS, the agencies never settled on what the secondary harm to wetlands would be. The Final EIS said total wetland acres destroyed or degraded could range as high as either 7,694 acres or 6,569 acres, and then stated that most of this damage was not “likely.” Yet, Army Corps allowed PolyMet to provide only 162 acres of replacement “credits” to cover damage or destruction due to secondary effects of the proposed PolyMet mine.

In July 2017, WaterLegacy submitted to the Army Corps an expert opinion by Jonathan Price, PhD, on the impacts of the proposed PolyMet mine on wetlands. Dr. Price concluded,

USACE [Army Corps] potentially severely under-predicts the potential damage to wetland function and consequently, would require insufficient compensation for indirect wetlands impacts.

Wetlands on proposed PolyMet mine site. Photo from the Department of Natural Resources.

Inadequate Wetlands “Replacement”

Both federal and state law allow wetlands destruction if the project proponent “replaces” the wetlands, which has come to mean restoring or preserving wetlands someplace else. WaterLegacy’s wetlands expert Morgan Robertson, Ph.D. showed that the proposed wetland replacement plan in the PolyMet final environmental impact statement (EIS) was outside both the St. Louis River watershed and the Lake Superior Basin and violated federal law.

As a result, PolyMet’s wetlands replacement plan was changed to provide replacement wetlands in the Lake Superior Basin and, potentially, in the St. Louis River watershed. This was a positive change. But the Army Corps new “wetlands replacement” plan lacks basic requirements to make sure benefits to wetland ecosystems in the new PolyMet wetland replacement plan are real.

WaterLegacy Comments

WaterLegacy submitted separate detailed comments and expert reports to oppose the PolyMet Section 404 permit as a violation of the Clean Water Act.

Read WaterLegacy Comments Opposing PolyMet Section 404 Permit (Dec. 14, 2015)

WaterLegacy argued against state certification of the PolyMet wetlands destruction permit.

Read WaterLegacy Comments Opposing PolyMet Draft NPDES Permit and 401 Certification (Mar. 16, 2018)



EarthJustice, representing several conservation groups, also filed suit in U.S. District Court  on September 10, 2019,  

Read the EarthJustice Complaint