This illustration of the planned Rosemont Mine shows where the copper ore will be processed and copper concentrate produced to be sent to a smelter.  

Opponents of the Rosemont Mine filed suit Wednesday to overturn the U.S. Army Corps of Engineers' recent approval of a permit for the $1.9 billion project.

The suit, filed in U.S. District Court, alleges that the Corps violated the Clean Water Act, the National Environmental Policy Act, the Administrative Procedures Act and several related rules and guidelines in approving the permit for the mine in the Santa Rita Mountains southeast of Tucson.

The Corps approved the permit on March 8. Its 81-page decision concluded that the project will serve the public interest, that its plan to mitigate for damages to washes on the mine site is adequate, and that some of the most damaging impacts that opponents say it will cause are not within the agency's legal scope of analysis for the project.

The permit allows Hudbay Minerals Inc. to discharge dredged and fill material for the mine project into nearly 38 acres of washes on the mine site.

The lawsuit, however, challenges all of those conclusions, hammering particularly hard at the Corps' refusal to consider any impacts beyond those related to the grading, clearing and grubbing of those washes. The suit notes that this position is a major change from the agency's original public notice for the permit back in 2011. At the time, the Corps said it considered the discharge of waste rock and tailings and the digging of the mine's open pit to all have impacts on federally regulated washes that need considering.

The lawsuit also repeatedly referred to the detailed and severe written criticisms made of the project over the years by the U.S. Environmental Protection Agency and Bureau of Land Management and the Arizona Game and Fish Department.

Filing the lawsuit were the opposition groups Save the Scenic Santa Ritas, the Center for Biological Diversity, the Sierra Club's Grand Canyon Chapter, and the Arizona Mining Reform Coalition, an umbrella organization representing 16 groups including the other three activist groups filing this suit. Also suing were the Tohono O'Odham, Pascua-Yaqui and Hopi tribes.

The Army Corps does not comment on pending litigation, said Edward Coffey, a Corps spokesman. Hudbay, which wasn't named as a defendant in the suit, didn't respond to a request from the Star for comment on the case.