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SRP Pumped Storage Project

Salt River Pumped Storage Project

Pumped storage hydropower provides long-duration energy storage that can help increase SRP’s supply of reliable, affordable and sustainable energy. Learn more about our plans to expand hydroelectric generation through the Salt River Pumped Storage Project.

On this page:

    About the project

    SRP has been operating pumped storage units on the Horse Mesa and Mormon Flat dams for over 40 years.

    As part of the Salt River Pumped Storage Project, SRP is exploring opportunities to expand pumped storage hydropower on the Salt River reservoir system.

    SRP is evaluating two potential sites for a new pumped storage hydropower facility to pair with Apache Lake on the Salt River. The pumped storage hydropower facility would require construction of a new reservoir to act as the upper reservoir and additional transmission infrastructure to connect to SRP’s existing 500-kilovolt (kV) Coronado-Silver King transmission line near the intersection of SR188 and SR288. The proposed pumped storage sites and transmission infrastructure routing options are depicted in the study area map.

    The results from the engineering design efforts, environmental surveying and public input will assist SRP in selecting the preferred pumped storage site and transmission routes for permitting efforts.

    As SRP adds significantly more solar to its power system, there will be a need for a diverse portfolio of long-duration energy storage to store solar generated during the day and dispatch it overnight to ensure reliable electric service around the clock.

    How pumped storage hydropower works

    Pumped storage hydropower facilities store and generate electricity by moving water between two reservoirs at different elevations.

    Morning and midday

    When electricity demand is lower and SRP has excess supply available, the turbines spin backward to pump the water back into the upper reservoir so it can be used again to generate power. As SRP adds more solar to the grid in the coming years, we expect that the amount of solar available will exceed demand during the morning and midday periods.

    Late afternoon and overnight

    To generate electricity when power from the plant is needed, water is released from the upper reservoir through hydropower turbines that rotate generators to produce electricity. The water flows into the lower reservoir where it stays until electricity demand lowers.

    Pumped storage project video

    Benefits of pumped storage hydropower

    Pumped storage hydropower provides a large-scale way to store and deliver electricity to customers. Below are some of the reasons we’re planning to add it to our power generation sources.

    Supports grid reliability

    Generating pumped storage hydropower helps SRP diversify our resource portfolio. That means the energy we produce is more reliable, more diverse, and less sensitive to supply chain or market shocks that could negatively impact prices.

    Boosts renewable energy supply

    Pumped storage hydropower can also play a key role in helping us store renewable energy that’s generated during the day so it can be used at night. One facility can provide 10 to 12 hours of energy storage.

    Reduces carbon intensity

    Another benefit of pumped storage hydropower is that it supports the growth of SRP’s renewable energy resource mix. This helps SRP on its path to meet its 2035 Sustainability Goals in the coming years and, ultimately, serve our customers and communities by providing reliable, affordable and sustainable power.

    Past success and future potential

    SRP has a long history of successfully operating hydropower generating facilities on the Salt River.

    Currently, SRP generates 265 megawatts (MW) of hydropower at the four dams located on the Salt River. That’s enough to power more than 60,000 average-sized homes. Two of those dams, Horse Mesa and Mormon Flat, have generators capable of pump-back operation with a total capacity of over 150 MW.

    The new pumped storage facility would have a capacity of between 1,000 MW and 2,000 MW — enough power to serve approximately 225,000 to 450,000 homes for 10 hours after each time the reservoir refills.

    Project timeline: Target in service by 2033

    Following engineering feasibility assessments and environmental permitting, the decision to begin construction would occur in 2027.

    This timeline would allow for a facility to be constructed and online by 2033 to help meet SRP's significant resource need in early 2030.

    Past events

    SRP hosted the following public meetings in November 2023. See the public meeting presentationDocument is a PDF.

    Date & Time Event Location
    Tuesday, Nov. 7, 2023
    8 a.m.–noon
    Stakeholder Workshop SRP PERA Complex
    1 E. Continental Dr.,Tempe, AZ 85288
    Tuesday, Nov. 7, 2023
    2 p.m.
    Virtual Stakeholder Workshop Online
    Monday, Nov. 13, 2023
    5:30 p.m.
    Virtual Local Community Public Open House Online
    Tuesday, Nov. 14, 2023
    5–7 p.m.
    Local Community Public Open House Bullion Plaza Cultural Center
    and Museum Gymnasium
    150 N. Plaza Circle, Miami, AZ 85539
    Wednesday, Nov. 15, 2023
    5–7 p.m.
    Local Community Public Open House Magma Ranch K-8 School Gymnasium
    10980 E. Desert Mountain Blvd., Florence, AZ 85132
    Monday, Apr. 22, 2024
    Noon-2 p.m.
    Virtual Stakeholder Workshop Online
    Tuesday, Apr. 23, 2024
    Noon-3 p.m.
    Stakeholder Workshop SRP Heritage Center
    1500 N. Mill Ave., Phoenix, AZ 85008
    Tuesday, Apr. 23, 2024
    5:30-7:30 p.m.
    Virtual Local Community Public Open House Online
    Wednesday, Apr. 24, 2024
    4:30-6:30 p.m.
    Local Community Public Open House Ffinch's Waterfront Kitchen
    28085 AZ-199, Roosevelt, AZ 85545
    Thursday, Apr. 25, 2024
    4:30-6:30 p.m.
    Local Community Public Open House Magma Ranch K–8 School (Gymnasium)
    10980 E. Desert Mountain Blvd., Florence, AZ 85132

    News archive

    See the latest project news and announcements below.

    Dec. 2, 2023
    SRP pursues plan to use solar, hydro energy to power thousands of Arizona homes

    Salt River Project is pursuing a plan to pump water uphill using solar power when that power is abundant during morning and midday hours.

    Read moreOpen new site.

    Public input process

    As this project moves forward, there will be a variety of opportunities for public input. SRP will provide more information here as opportunities for public input become available.

    Contact us

    If you have questions about the project, please call (602) 236-2872, email 2872line@srpnet.com or complete the form below.

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