When President Joe Biden ran for office, he pledged support for tribal communities. Now one Arizona tribe is calling on Biden to fulfill that pledge.

The Havasupai Tribe has written a letter to the secretary of Energy asking her to exempt Pinyon Plain Mine, located near the Grand Canyon, from a uranium subsidy program. The tribe, which lives inside the Canyon, fears that the program, along with rising uranium prices, might bring the mine into production, which could contaminate the region’s groundwater.

Stuart Chavez, a member of the Havasupai Tribe, said the tribe has battled the mine for decades.

“We’re protecting the water, we’re protecting the earth, we’re protecting all elements that are very dear to not only our tribe but also Mother Earth,” Chavez said.

Although the war in Ukraine has led to higher prices, industry analysts say the U.S. has enough uranium stockpiled to last for well over a decade.