Tuesday's unanimous vote by the board that oversees state-owned property will allow Ohio-based Signal Peak Energy to double the size of its Bull Mountain mine, reports the Billings Gazette.
The planned expansion covers 7160 acres and is expected to generate $US127.2million from taxes and royalties.
Despite resistance from local environmental groups, the expansion was approved due to the positive contribution it would make to the local economy.
"Those 325 people who work at Bull Mountain combined make about $40 million a year,” board member Tim Fox said. "That's money that is spent in local stores and is important to the economy."
The state Department of Environmental Quality agreed to the mine expansion last October while The federal Bureau of Land Management approved the leasing of federal coal reserves involved in the expansion in 2012.
