Two new federal lawsuits say that permits issued for PolyMet Mining’s proposed $1 billion copper-nickel mine in Minnesota violate federal laws, including the Clean Water Act.

The lawsuits, both filed Tuesday in U.S. District Court in Minnesota, come as the state’s first copper-nickel mine moves toward construction after years of controversy.

In one, the Fond du Lac band of Lake Superior Chippewa sued the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers over two of PolyMet’s permits: a disputed water-quality permit issued by state pollution regulators and a permit to dredge and fill wetlands, issued by the U.S. Army Corp of Engineers.

“One of the many claims made by the band is that the EPA and Army Corps both failed in their obligations to the band as a downstream tribe ... to prevent violation of the band’s water quality standards, particularly the standard for mercury,” said Paula Maccabee, a lawyer with WaterLegacy, who is not party to the lawsuits.

The handling of the two permits violated laws governing treaties with Indian tribes, the Clean Water Act, the National Environmental Policy Act and the Administrative Procedure Act, which governs how federal agencies establish regulations, the lawsuit says. The band asks for an injunction to stop all activities related to PolyMet’s dredge and fill permit.

In the other, four environmental groups — Earthjustice, Friends of the Boundary Waters Wilderness, the Minnesota Center for Environmental Advocacy and the Center for Biological Diversity — sued the U.S. Army Corps of Engineers over the dredge and fill permit, saying it, too, violates the Clean Water Act and the National Environmental Policy Act. It also asks for an injunction to stop work under the permit.

“The PolyMet mine would result in the single largest permitted destruction of wetlands in the history of Minnesota,” said Chris Knopf, executive director of Friends of the Boundary Waters Wilderness, in a news release.

The EPA said it does not comment on ongoing litigation; the U.S. Army Corps of Engineers did not immediately respond to a request for comment. PolyMet spokesman Bruce Richardson said the company was reviewing the lawsuits.

The Fond du Lac band lives about 70 miles downstream from the site of the proposed copper-nickel mine, which is near Babbitt, Minn., a wetlands area that drains into the Partridge and Embarrass Rivers and into the St. Louis River that runs to Lake Superior. The mine operations will destroy some 900 acres of the peat bog-dominated wetlands and put the St. Louis River at risk of contamination from heavy metals, the lawsuit said.

“The St. Louis River is the most significant and utilized fishery on the Reservation,” lawyers for the band said in the suit.

The lawsuit describes how the band, which has its own scientific water expertise and analysis, wrote to the Corps of Engineers and the EPA three times between late 2018 and early 2019 about its concerns and requested a hearing but was met with silence from both agencies.

It also describes last year’s episode in which the significant concerns the EPA Chicago staff had with PolyMet’s water-quality permit were kept out of the public record. The Minnesota Court of Appeals has put the water permit on hold pending a Ramsey County District Court hearing on alleged “irregularities” in the processing of that permit, one of three investigations into the processing of the permit.

Named defendants in the Fond du Lac lawsuit also include Cathy Stepp, the appointed administrator of the EPA’s Chicago office; EPA administrator Andrew Wheeler; Samuel Calkins, district engineer at U.S. Army Corps of Engineers, St. Paul District; and Ryan McCarthy, acting secretary of the U.S. Army Corps of Engineers.

The environmental groups’ lawsuit also names McCarthy and the corps.