Minntac Tailings Basin

What is 8,700 acres in size, located in the headwaters of Boundary Waters Canoe Area watershed rivers, and has effectively resisted permit controls on sulfate and other water pollution for a quarter of a century? The U.S. Steel Minntac tailings basin is the poster child for Minnesota’s failure to control mining pollution, even when there is clear evidence that the pollution has violated Minnesota water quality standards and decimated downstream wild rice.

U.S. Steel, Minntac tailings basin. Photo by Creative Commons.

Is Minntac tailings basin pollution controlled?

The history of Minntac permits is one of lapsed permits, inadequate regulation, and insufficient control of pollution. A Minntac tailings basin water pollution permit was issued in 1987 and expired in 1992. But it took until 2018 — or more than 25 years — for the Minnesota Pollution Control Agency (MPCA) to reissue a new permit. Under pressure from lawsuits, MPCA finally proposed draft water pollution permits for the Minntac tailings basin in 2014 and 2016. These draft permits were inadequate to protect water quality or wild rice, so WaterLegacy, tribes, and allies submitted detailed and highly critical comments. The U.S. Environmental Protection Agency (EPA) also submitted a comment stating that MPCA’s proposed draft Minntac permit would violate the Clean Water Act.

On November 30, 2018, despite the opposition by EPA, WaterLegacy, tribes, and allies, MPCA issued a final permit that failed to t set water quality-based limits on Minntac tailings basin direct pollution of wetlands and streams and did not control Minntac discharge of pollution through groundwater. Water quality, fish, and wild rice were not protected.

In 2020, it was revealed that from 2017 to 2019 the U.S. Environmental Protection Agency (EPA) was pursuing a federal enforcement action against U.S. Steel for Minntac tailings basin sulfate pollution affecting wild rice. But, rather than proceeding on its own to enforce the Clean Water Act, which could have meant a multi-million dollar fine for U.S. Steel as well as strict cleanup requirements, the Trump EPA asked MPCA to approve the enforcement action. MPCA opposed enforcement. EPA failed to act, and enforcement was stalled.

E & E News investigated and reported on this classic Minnesota mining fiasco.    

Read: State balks, EPA bails on mining pollution case, E & E News, Sept. 17, 2020

Minntac tailings basin. Photo from GLIFWC.

What’s the current status of the Minntac pollution permit and appeal?

WaterLegacy and the Fond du Lac Band of Lake Superior filed appeals from the MPCA’s issuance of the Minntac water pollution permit on the last day of 2018. WaterLegacy’s appeal challenged: 1) MPCA’s failure to set pollution limits on direct discharge from the Minntac tailings basin; and 2) MPCA’s failure to control discharge from tailings basin seepage through groundwater affecting downstream waters and wild rice. However, WaterLegacy supported MPCA conditions that would begin to limit Minntac tailings basin sulfate pollution of groundwater.

After briefing and oral argument, the Minnesota Court of Appeals issued a decision on December 9, 2019, that cut both ways. The Court ruled that the MPCA failed to require water quality-based effluent limits on direct Minntac discharge in violation of the Clean Water Act. The Court sent this portion of the permit back to MPCA due to evidence that pollution capture for direct surface seepage used by Minntac was not effective.

However, the Court affirmed MPCA’s conclusion that any pollution that traveled through groundwater before polluting wetlands, rivers, and lakes was not covered by the Clean Water Act. The Court also ruled in favor of U.S. Steel that Class 1 groundwater standards did not apply to protect groundwater from Minntac polluted seepage.

Minnesota Supreme Court Review

WaterLegacy and the Fond du Lac Band petitioned the Minnesota Supreme Court to review the Court of Appeals’ decision that pollution through groundwater need not be controlled under the Clean Water Act. On February 26, 2020, the Minnesota Supreme Court – which accepts only about 5 percent of petitions – agreed to take the case.

Important U.S. Supreme Court Decision

While the Minntac appeal to the Minnesota Supreme Court was pending, the U.S. Supreme Court decided a related Clean Water Act case coming out of Maui, Hawaii. In County of Maui v. Hawai’i Wildlife Fund, the Supreme Court ruled that a position like that taken by MPCA for the Minntac permit – that no pollution through groundwater could ever be controlled by the Clean Water Act – created an unacceptable loophole. The Maui case held that if discharge through groundwater was the “functional equivalent” of direct discharge it must be regulated.

Minnesota Supreme Court Victory

On February 10, 2021, the Minnesota Supreme Court ruled that both the MPCA and the Court of Appeals were wrong in their blanket denial that the Clean Water Act did not regulate seepage through groundwater to surface water. The Court also ruled that Class 1 drinking water standards applied to Minntac seepage to groundwater and did not disturb the Court of Appeals’ ruling that the MPCA must set effluent limits for any direct Minntac seepage to surface water. WaterLegacy and the Fond du Lac Band won on all counts.

The Star Tribune reported:

The ruling is a clear win for state regulators and environmental groups, who argued the state was allowed to limit sulfate pollution into groundwater — not just surface water —under the Clean Water Act.

“In U.S. Steel’s zeal to prevent any regulation of its own pollution, the company had put all of Minnesota’s regulation of groundwater at risk,” said Paula Maccabee, lawyer for the environmental group WaterLegacy, which appealed the case to the state Supreme Court along with the MPCA and the Fond du Lac Band of Lake Superior Chippewa.

The critical question remains – when will pollution controls actually be established and enforced at the U.S. Steel Minntac tailings basin?

Minntac Tailings Basin Permit History

Would you like to know the back story on the U.S. Steel Minntac tailings basin? Read Stephanie Hemphill’s summary of the implications of Minnesota’s failure to regulate Minntac pollution:

The legal issues surrounding Minnesota’s largest taconite mine are complicated, but people concerned about a possible future of copper-nickel mines in the water-rich northern part of the state look at Minntac’s history and worry that the state’s regulatory agencies may not have the backbone to enforce state laws on any kind of mine.

Read the Nov. 2020 Agate here.

Minntac 1987 National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) water pollution permit expires in 1992. It is “administratively extended” by MPCA for 26 years before an updated permit is reissued. The permit contains no limit on sulfate to protect wild rice.


MPCA releases a pre-publication draft Minntac water pollution permit. This permit does not require compliance with Minnesota’s 10 mg/L sulfate standard.


MPCA circulates another draft Minntac water pollution permit. The permit does not require compliance with Minnesota’s 10 mg/L sulfate standard. WaterLegacy’s Advocacy Director states in the Timberjay that MPCA’s draft Minntac permit “stands the Clean Water Act on its head and lets the polluter set the standard.”


U.S. Steel requests a variance from even the few permit conditions proposed by MPCA for the Minntac tailings basin. This variance is denied by MPCA.


MPCA grants a final permit to U.S. Steel for the Minntac tailings basin on November 30, 2018. The final Minntac permit contains no limits on sulfate to protect wild rice and, in fact, contains no water quality-based effluent limits at all. The permit requires no controls on tailings basin seepage through groundwater to surface water to meet water quality standards in affected wetlands, streams and lakes. Ever.


Minntac Mine Expansion without Environmental Review

Many Minnesotans believe that mine expansions go through a rigorous environmental review process. Nothing could be further from the truth.

Aerial photo of huge expansion of Minntac mine, tailings basin and processing facility (documents filed by U.S. Steel in 2012)

The Minntac mine has been continually and incrementally expanded for decades without ever going through an environmental impact statement (EIS) study of harm to the environment or alternatives to minimize that harm. The most recent Minntac expansion was in 2012. The expansion proposed impacts to 483 acres, including 67 acres of wetlands and excavation of nearly 2 billion tons of ore, waste rock, and overburden (natural rock and soil above the ore body). WaterLegacy and our allies called for an EIS and an investigation of water quality issues and alternatives.

The result? No EIS was ordered by either the Minnesota Department of Natural Resources (DNR) or the U.S. Army Corps of Engineers.

MPCA approved the certification of the Minntac permit under the Clean Water Act, despite the fact U.S. Steel was in violation of even its decades-old weak permit. WaterLegacy commented:
Neither federal nor state law allows the MPCA to certify the proposed Minntac Mine Expansion. This project is a textbook case of what Section 401 was intended to prevent – the increase of discharge that already violates water quality standards by a polluter operating outside the law for a matter of decades.