(CN) — Three environmental groups sued the Army Corps of Engineers in federal court Tuesday, seeking to block a Minnesota copper mine they say would destroy wetlands and wildlife habitat.
The Minnesota Center for Environmental Advocacy, the Center for Biological Diversity and the Friends of the Boundary Waters Wilderness sued the Corps and acting Secretary of the Army Ryan McCarthy in St. Paul Federal Court.
They want to stop the NorthMet Mining Project, a copper-sulfide ore mine in the Lake Superior watershed. Polymet Mining Corp., a Canadian company, has proposed the project.
The environmentalists asked for an injunction to stop the Corps from issuing a permit for the mine, which they say would violate the Clean Water Act and the National Environmental Policy Act.
“The Corps’ approval of the NorthMet Mine, based on a plainly inadequate environmental review and inadequate consideration of mandatory factors under the law, injures the health, recreational, economic, professional, scientific and aesthetic interests of plaintiffs and their members,” the complaint states.
The conservation groups say that when exposed to air and water, sulfide ore will produce pollutants called “acid mine drainage.”
“The pollutants in this runoff are highly damaging to fish, vegetation, and water quality generally,” the complaint states. “Moreover, the sulfates in runoff or wastewater from mining sulfide ore are highly damaging to wild rice.”
According to the lawsuit, Polymet proposed extracting one-third of the non-ferrous minerals at the site. The mine could produce up to 32,000 tons of ore per day, the complaint states.
“In the Final Environmental Impact Statement for the Mine, the Corps determined that the mine would cause the permanent loss of 913.8 acres (the equivalent of almost 700 football fields or 1.5 square miles) of high quality wetlands due to dredge and fill activity,” according to the 45-page complaint.
The plaintiffs say the Corps did not “detail the type and magnitude of loss” that the mine would create.
Polymet submitted a revised application for a smaller project that included mitigation of loss of wetlands, but “The Corps did not provide a public notice requesting comment on these significant revisions to the 404 permit,” according to the complaint.
The Corps required Polymet to purchase 1,278 acres worth of wetland mitigation credits from the Lake Superior Wetlands Bank, the lawsuit states.
But the plaintiffs say the mine would increase mercury levels in the St. Louis, Partridge and Embarrass rivers.
“However, the Final Environmental Impact Statement does not analyze the extent of the increase or the attendant impacts on water quality standards and fish tissue or human health, stating only that the effect of increased methylated mercury will ‘decrease with distance downstream,’” according to the complaint.
The plaintiffs also warned of a dam-failure disaster similar to one that happened in a Brazilian mine in January 2019.
The Center for Biological Diversity was also part of a 2017 lawsuit that said the mine would threaten the habitats of the gray wolf, Canada lynx and northern long-eared bat.
The environmental groups are represented by Janette Brimmer and Jaimini Parekh, of Seattle.