October 6, 2026 - Two environmental groups are appealing a federal agency’s decision to extend the life of a Navajo Nation-owned coal mine to 2136.

The groups wrote in an appeal to the U.S. Department of the Interior that prolonging the life of the Navajo Mine in northwestern New Mexico could raise costs for ratepayers and pollute the air as well as groundwater. They also say the expansion would require some Navajo families to relocate.

“The local impacted community has already borne so much impact from this industry,” said Mike Eisenfeld, the energy and climate program director for San Juan Citizens Alliance.

The groups appealing to the Interior Department include Tó Nizhóní Ání, a Navajo-led nonprofit that says it works to empower Indigenous communities affected by coal. The other is San Juan Citizens Alliance, a Durango-based environmental nonprofit.

In the past, retired Navajo coal miners in New Mexico and Arizona have said they suspect they have deadly black lung disease, otherwise known as coal workers’ pneumoconiosis, from working at operations like the Navajo Mine.

The Interior Department did not immediately respond to KNAU’s request for comment on the groups’ claims.

In September, the U.S. Office of Surface Mining, Reclamation and Enforcement greenlit the expansion of the mine by approving the so-called No Name Permit, which would allow extraction of over 500 million tons of coal across about 9,042 acres of land. The Office of Surface Mining is housed within Interior.

Eisenfeld said the single public meeting conducted by the office was insufficient given the size of the proposed expansion.

“The one scoping meeting they conducted was very marginal,” he said. “This should have had a way, way more expansive participatory zone.”

The Navajo Mine is operated by Navajo Transitional Energy Company, or NTEC, which is itself owned by the Navajo Nation government.

NTEC and its supporters have previously advocated for the expansion of the mine in order to bolster the tribal nation’s economic stability. The permit’s name comes from the No Name Arroyo, a dry wash that runs through the project area.

The mine’s only customer is the Four Corners Power Plant, which sits near Fruitland, New Mexico. It’s run by the utility company Arizona Public Service.

Last week, APS publicly confirmed the utility signed a contract with NTEC that could keep the power plant alive until 2038. It had originally been slated for closure by 2031.

The expansion of the Navajo Mine is the largest amount of coal ever approved for extraction on Native American land in the U.S., according to the Office of Surface Mining.