Assuming there are hydro or nuclear plants nearby. Coal mining and power generation is a massive percentage of the income for the Navajo. With the coal going away they can't dam the non-existent rivers in the desert to build a hydro plant.
The cooling pond would become the upper reservoir but may need to be enlarged for more potential as a battery.
That keeps jobs in the area.
EDIT: In the case of the Navaho the mine isn't next door to the plant but it does have water. Maybe a thermal plant would make sense with natural gas backup/overnight reheat and repurpose the current plants steam turbines.