April 18, 2019 - Montana state regulators have given final approval to a 70-million ton expansion of a southeastern Montana coal mine that provides fuel to the Colstrip power plant.

The state Department of Environmental Quality said Thursday's approval of the 10-square-mile expansion would allow the Rosebud mine to stay open until the late 2030s.

Officials say mining will not be allowed within a small portion of the expansion area to prevent damage to area water supplies.

Separate approval is still needed from the U.S. Department of Interior.

Mine owner Westmoreland Coal Co., which is based in Englewood, Colorado, recently emerged from bankruptcy after selling off some of its assets.

Colstrip is one of the largest coal-burning plants in the Western U.S.