The West’s largest coal-fired plant will remain open through the end of 2019.

On Wednesday, the U.S. Department of the Interior announced that it has approved the lease for the Navajo Generating Station.

Without the final approval, the coal-fired plant in the northeast corner of Arizona would have closed at the end of the year. Instead, it will operate for the next two years.

After that, the owners of the plant, including Salt River Project, Arizona Public Service and Tucson Electric Power, will pull out because of low natural gas prices that the utilities say make coal generation no longer economical.

The plant is a critical economic driver and source of revenue for the Navajo and Hopi tribes, employing more than 600 people. It also emits more greenhouse gases than almost any other power plant in the country.

So far the tribes have not been able to find any new owners to assume control of the plan after 2019.