HELENA, Mont. — A lawsuit filed by two environmental groups charges that the state Land Board's decision to lease Otter Creek coal tracts runs afoul of the Montana Constitution and asks a judge to undo the lucrative deal.

The state recently leased the massive coal tracts to mining giant Arch Coal Inc. for a bonus bid of $86 million — and the promise of billions of dollars in taxes and royalties over the coming decades if the mine is developed as hoped.

But in a lawsuit filed Wednesday in District Court in Broadus, the Northern Plains Resource Council and the National Wildlife Federation argued that the Land Board failed to recognize constitutional guarantees of a clean environment when it made its decision.

The Land Board, made up of the state's top elected officials, including the governor, endorsed the plan in March on a split 3-2 vote after several contentious hearings.

St. Louis-based Arch Coal subsequently paid the $86 million upfront obligation as it readies plans to get a railroad in place and start environmental assessments. The company has said the coal could serve growing economies in Asia.

The lawsuit argues that the board did not consider the effect of coal mining on water and air quality, wildlife, cultural resources, or farms and ranches. The groups argue Otter Creek could become the biggest mine in the country, contribute to area pollution, and ruin the landscape.

"The Land Board has no business selling off coal mining rights to out-of-state developers without first looking into what it might mean for our land and groundwater," Mark Fix, an area rancher with Northern Plains, said in a statement. "This mine might be good for China, but it's not good for Montana."

Sourced from The Associated Press