Flagstaff, Ariz. • A federal appeals court has upheld the dismissal of a lawsuit aimed at shutting down a coal-fired power plant and adjacent mine near the Arizona-New Mexico border.

Environmental groups had targeted a 25-year lease extension for the Navajo Mine and the Four Corners Power Plant in northwestern New Mexico. They alleged the U.S. government did not consider clean-energy alternatives or possible effects on endangered species.

A lower court had tossed the case because the mine is owned by a Navajo Nation corporation, meaning it is shielded from legal challenges.

The 9th Circuit U.S. Court of Appeals agreed Monday, saying the case cannot move forward without the corporation as a defendant.

The power plant is one of three in the region that are scaling back operations as utilities shift toward natural gas and renewable energy sources.