Colorado, New Mexico, Utah and Wyoming are resisting the deal because it would allow the Navajo and Hopi to lease water to cities downstream, likely the growing towns around Phoenix.

A deal to bring Colorado River water to Native American communities in northern Arizona, where a third of homes lack running water, is being blocked by neighboring states, caught up in a broader battle over how to divide the dwindling river.

The largest tribal water rights settlement in U.S. history — the product of decades of negotiations to secure water for the Navajo Nation, Hopi Tribe and San Juan Southern Paiute Tribe — was on the verge of being realized before Colorado, New Mexico, Utah and Wyoming stepped in to oppose it being codified by Congress.