BOISE — Environmental harms, including to sage grouse habitat, were not adequately addressed by the U.S. Bureau of Land Management in approving a new phosphate mine in southeast Idaho, a federal judge has ruled.

The Center for Biological Diversity, the Western Watersheds Project and WildEarth Guardians sued the Bureau of Land Management and the Interior Department over BLM’s approval of the Caldwell Canyon open-pit phosphate mine in southeast Idaho.

Monsanto subsidiary P4 Production LLC would operate the mine, about 13 miles from Soda Springs. Ore would be transported by truck and rail to a plant that Monsanto parent Bayer AG owns to produce glyphosate herbicide used in Roundup products.

U.S. District Judge B. Lynn Winmill granted summary judgments in favor of the plaintiffs on Jan. 24, saying BLM failed to consider the indirect effects of processing ore at the plant, and that the agency “failed to take a hard look at the direct, indirect and cumulative impacts on greater sage grouse.”

He granted summary judgments in favor of the defendants on claims related to the Clean Water Act, and to claims that the Bureau inadequately considered water resource impacts and failed to consider the required range of alternatives in developing and approving a Final Environmental Impact Statement.

The decision means the Final EIS “was unlawful to the extent that it did not consider the effects of ore processing at the Soda Springs plant and the effects on greater sage grouse in the project area,” Sarah Stellberg, an attorney with Advocates for the West in Boise, said in an interview.

BLM cannot comment on the decision but is evaluating it and will address concerns it raises, said Bruce Hallman, public affairs officer for the Idaho Falls District.

The environmental groups in 2021 challenged a BLM decision to approve about 1,559 acres to be mined.

The ruling is a “critical victory for sage grouse and all the people and wildlife that rely on this fragile, irreplaceable ecosystem,” Hannah Connor, an attorney at the Center for Biological Diversity, said in a release. The ruling confirms “that the government can’t arbitrarily reduce this area’s value for sage grouse habitat and ignore phosphate mining pollution.”

Habitat destruction from mining and agriculture poses a serious risk to southeast Idaho’s sage grouse population, and BLM ignored its responsibility to protect habitat, said Erik Molvar, a wildlife biologist and Western Watersheds executive director. The agency also “failed even to take the basic step of describing and considering the impacts that this phosphate strip mine would have on sage grouse survival and connectivity.”