PolyMet Mining Corp.'s land swap deal with the U.S. Forest Service to secure land for its preproduction-stage NorthMet copper-nickel mine in Minnesota is facing a second lawsuit by environmental groups.

In a suit filed in a U.S. District Court against the Forest Service, WaterLegacy alleged that the transfer approval violated the federal land policy and management act by undervaluing the land.

PolyMet announced Jan. 9 that it secured 6,650 acres of federally owned forests and wetlands in exchange for 6,690 acres of land scattered elsewhere in the state in a deal with the Forest Service.

The next day, the Center for Biological Diversity and Earthworks filed a notice of intent to sue the U.S. Fish and Wildlife Service and the Forest Service under the Endangered Species Act for approving the NorthMet project.

According to a Jan. 30 statement from WaterLegacy, the Forest Service valued the site proposed for the PolyMet mine at US$550 per acre, comparing the figure to an average US$3,885 per acre paid by Kennecott Exploration Co. for land in Minnesota's Aitkin County from 2012 to 2016.

"WaterLegacy's board and thousands of other citizens across Northeastern Minnesota are tired of seeing Minnesota's Superior National Forest lands and Lake Superior watersheds devalued in order to serve the interests of PolyMet and its foreign investors," the nonprofit's attorney, Paula Maccabee, said.