A House committee Wednesday approved a bill that would allow the Salt River Project to build a new reservoir near Lake Apache solely for the purpose of generating electricity.
SRP has been comparing two sites in a canyon above Lake Apache that could build a new reservoir that would act like a battery that would release water into Lake Apache through a hydroelectric dam when SRP customers in the Phoenix area needed power.
The SRP will pump water from approximately 1,000 feet of Apache Lake up the mountain to replenish a 100- to 200-acre reservoir, possibly using grid surplus electricity from a solar power plant.
Arizona Republican Rep. David Schweickert introduced a bill that would allow the project by extending the land available for power projects by an additional two miles south of Lake Apache, where two sites are being evaluated. Rep. Greg Stanton, Arizona Democrat, Rep. Debbie Lesko, Arizona Republican. and Ruben Gallego of the Arizona Democratic Party.
Both candidate sites include US Forest Service land that will be placed under the administration of the Bureau of Reclamation for the project. The law excludes land from the Tonto National Monument or the Superstition Wilderness from the affected areas.
The House Natural Resources Committee unanimously passed HR 1607 Wednesday.
It is currently awaiting a full vote in the House. Senators Mark Kelly (Democrat, Arizona) and Senator Kirsten Cinema (Iye, Arizona) introduced accompanying bills to the Senate.
“This will increase the availability of affordable and reliable energy in central Arizona,” Schweickert said in a post-vote statement.
Stanton cited a recent electricity demand record breaking in Arizona during a heatwave as a reason to support the project.
“Not only will pumped storage help integrate renewable energy into the grid, but it will also increase the flexibility and reliability of the overall system, and importantly, it will help Arizona homes and businesses save on energy bills when they need it most,” Stanton said in a post-vote statement.
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Reservoirs help supply electricity
SRP also plans to add a new solar power plant to its grid, along with several large lithium-ion batteries to accompany it. The battery will allow SRP to store electricity generated during the day and supply it to customers after sunset.
“Pumped storage” reservoirs work similarly, releasing water to generate electricity when it is most needed by the grid.
SRP expects that each time this reservoir is refilled, it can generate nearly enough electricity to power 250,000 homes for 10 hours.
The SRP maintains Apache near full water levels via the Hose Mesa Dam. That fact, combined with the topography, makes the area an ideal location for such a project, officials said.
Already, SRP is using what it calls “pumpbacks” to generate electricity from the Horse Mesa Dam on Lake Apache and the Mormon Flat Dam on Canyon Lake.
Pumpbacks use electricity when demand is low to move water upstream through the dam’s turbines. The SRP then releases the water to generate electricity when demand is high and customers need it.
Pumped storage is slightly different from existing pumpback facilities as it uses additional reservoirs rather than exchanging water between existing reservoirs.
The new project will have the capacity to generate more than six times the power of those pumpback sites.
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The new reservoir will operate primarily to generate electricity without interrupting the water supply downstream, which is the primary purpose of existing dams on the Salt River.
The new reservoir holds about one-sixth that of Canyon Lake, significantly smaller than Apache and Roosevelt.
The pumped pool will hold 10,000 to 20,000 acre feet of water. One acre-foot is approximately 326,000 gallons. Apache has approximately 245,000 acre feet. President Roosevelt has over 1.5 million.
Water users will notice that Lake Apache rises and falls slightly as the new reservoir fills and empties.
SRP has signed a contract for engineering and design work. The final cost is not yet known as SRP officials are still evaluating the site, size and design.
The SRP will set up power facilities near the Roosevelt Dam or the Horse Mesa Dam, two dams on the edge of Lake Apache.
SRP hopes to have the new facility operational in 2032, when the Coronado Power Station coal-fired power plant in eastern Arizona is scheduled to close.
Please contact reporter Ryan Randazzo. ryan.randazzo@arizonarepublic.com or 602-444-4331. follow him on twitter @UtilityReporter.
