By Ryan Randazzo || The Arizona Republic
Salt River Project is comparing two sites in canyons high above Apache Lake where it could build a new reservoir, but this man-made lake would not allow water skiing or fishing.
And it wouldn’t serve to boost the region’s water reserves. SRP has different proposals to do that.
Instead, the small reservoir would function like an electric battery, releasing water through a hydropower dam and into Apache Lake when electricity is needed for SRP customers in the Phoenix area.
Once emptied, it would use surplus power on the grid, likely from solar plants, to pump water from Apache Lake about 1,000 feet below to refill.
SRP anticipates each refill of this “pumped storage” reservoir could generate approximately enough power to serve 250,000 homes for 10 hours.
Even in years with little rainfall, SRP maintains Apache’s water level at near full via Horse Mesa Dam. That fact, combined with the topography, makes the area ideal for such a project, officials said.
“For pumped storage to work you have to have a few important ingredients, one is a reliable water supply,” said Ron Klawitter, manager of water system projects for SRP. “Two is topography that allows for not only the elevation change between the two reservoirs but also the geography to construct a reservoir.”
The project is at least a decade from operating, but SRP has signed a contract for engineering and design work, and Arizona’s representatives in Congress introduced federal legislation to place the two possible sites under control of the Bureau of Reclamation, like the rest of SRP’s operations on the Salt River.
The final costs are not yet known because SRP officials are still evaluating the site, size and design.