Horse Mesa
Pumped storage power plant in Maricopa County, Arizona. 119.6 MW of nameplate capacity across 3 generators, operated by Salt River Project.
Also known as Horse Mesa Power Station · EIA plant 145
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 119.6 MWPumped storage 99.8 · Hydro 19.8
- Generators
- 3 operatingEIA-860M, August 2026
- Operating since
- April 1927First generator online
- Operator
- Salt River ProjectEIA operator ID 16572
- Grid
- SRPBalancing authority SRP
- Price nodes
- None linkedNo verified ISO node
- Location
- Maricopa County, AZ33.5907, −111.3440
- EIA plant ID
- 145EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Horse Mesa produces
Free · EIA-923Net generation, 2025
87.9 GWh
87,872 MWh, final
Capacity factor, 2025
Not reported
2024: Not reported
January to July 2026
48.2 GWh
Provisional
Range, 2015 to 2025
21.9–127.6
GWh a year. Low 2017, high 2023
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | 222,126 | Not reported | 12 of 12 |
| 2001 | 230,519 | Not reported | 12 of 12 |
| 2002 | 107,706 | Not reported | 12 of 12 |
| 2003 | 231,646 | Not reported | 12 of 12 |
| 2004 | −5,223 | Not reported | 12 of 12 |
| 2005 | 63,065 | Not reported | 12 of 12 |
| 2006 | 102,438 | Not reported | 12 of 12 |
| 2007 | 64,580 | Not reported | 12 of 12 |
| 2008 | 52,806 | Not reported | 12 of 12 |
| 2009 | 120,498 | Not reported | 12 of 12 |
| 2010 | 145,079 | Not reported | 12 of 12 |
| 2011 | 73,934 | Not reported | 12 of 12 |
| 2012 | 98,074 | Not reported | 12 of 12 |
| 2013 | 41,102 | Not reported | 12 of 12 |
| 2014 | 15,396 | Not reported | 12 of 12 |
| 2015 | 41,225 | Not reported | 12 of 12 |
| 2016 | 45,429 | Not reported | 12 of 12 |
| 2017 | 21,869 | Not reported | 12 of 12 |
| 2018 | 50,123 | Not reported | 12 of 12 |
| 2019 | 41,054 | Not reported | 12 of 12 |
| 2020 | 52,033 | Not reported | 12 of 12 |
| 2021 | 79,532 | Not reported | 12 of 12 |
| 2022 | 77,744 | Not reported | 12 of 12 |
| 2023 | 127,574 | Not reported | 12 of 12 |
| 2024 | 98,355 | Not reported | 12 of 12 |
| 2025 | 87,872 | Not reported | 12 of 12 |
| 2026 (provisional, partial year) | 48,178 | Not reported | 7 of 7 |
* 2026 covers January to July and is provisional. Capacity factor is net generation divided by nameplate capacity times the hours of each reported month.
Power prices and basis
Free accountNo verified ISO price node is linked to this plant, or its price history could not load.
Emissions
Free · EPA CAMPDNo EPA emissions units are linked to this plant.
Water use
Free · EIA-923 cooling, USGSNo EIA cooling-water record for this plant in 2024. Plants without steam cooling, such as wind, solar and batteries, do not report cooling water.
Generators
Free · EIA-860M| Generator | Technology | Nameplate MW | Online since |
|---|---|---|---|
| HM1 | Conventional Hydroelectric | 9.9 | April 1927 |
| HM2 | Conventional Hydroelectric | 9.9 | April 1927 |
| HM4 | Hydroelectric Pumped Storage | 99.8 | June 1927 |
Ownership and offtake
ProOwnership and offtake are part of Pro
Owners and their shares, parent companies, and power purchase agreements with their buyers. EIA-860M lists Salt River Project as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
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Power plants near Horse Mesa
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Questions about Horse Mesa
How much power does Horse Mesa produce?
Horse Mesa reported 87,872 MWh (87.9 GWh) of net generation in 2025. From January to July 2026 it reported 48.2 GWh, which is provisional.
Where is Horse Mesa?
Horse Mesa is in Maricopa County, Arizona, at 33.5907, −111.3440. It is in the Salt River Project balancing area (SRP).
Who operates Horse Mesa?
EIA-860M for August 2026 lists Salt River Project as the operator (EIA operator ID 16572). The operator is not always the owner.
When did Horse Mesa start operating?
Its first generator began operating in April 1927, according to EIA-860M.
Sources
- EIA-860 2025 (final) and EIA-860M August 2026: plant, generators, capacity, operator and location
- EIA-923 monthly net generation, 2000 to July 2026 (2026 provisional)
- Plant names from OpenStreetMap, © OpenStreetMap contributors (ODbL)
Page updated 2026-10-04 from the InfraMap data build. Methodology · Data sources · EIA plant page