Horse Mesa — Plant Summary
- EIA Plant ID
- 145
- Capacity
- 131.3 MW
- Primary Fuel
- Hydro
- Technology
- Conventional Hydroelectric, Hydroelectric Pumped Storage
- Status
- Operating
- Location
- Maricopa, AZ
- Operating Since
- 1927
- Generators
- 4
- Operator
- Salt River Project
- Parent Company
- Salt River Project
- Annual Generation
- 87,872 MWh
- Capacity Factor
- 7.6%
- Balancing Authority
- Salt River Project
- ISO/RTO
- —
- NERC Region
- WECC
Horse Mesa
OperatingHydroHybrid
Ranked #4 of 11 Hydro plants in AZ#147 of 1454 nationally
131.3 MW Conventional Hydroelectric (32 MW) + Hydroelectric Pumped Storage (100 MW) operating in Maricopa, AZ — Salt River Project
EIAGEMWD
131.3 MW
Nameplate Capacity
4
Generators
units
Hybrid (2)
Technology
Conventional Hydroelectric + Hydroelectric Pumped Storage
1927
Operating Since
Location
Coordinates
33.5907, -111.3440
County
Maricopa, AZ
Nearby Plants
- Mormon FlatHydro63.5 MW · 10.1 km
- Stewart MountainHydro13 MW · 18.0 km
Ownership & Operator
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | Salt River Project | US Bureau of Reclamation [100%] | — |
| Owner(s) | Salt River Project | Salt River Project | — |
| Status | Operating | operating | — |
Ownership Chain
About
The Horse Mesa Dam is a concrete thin arch dam located in the Superstition Mountains, northeast of Phoenix in Maricopa County, Arizona.
Read more on WikipediaHorse Mesa is a 131.3 MW hydroelectric power plant located in Maricopa County, Arizona. The plant, which began operating in 1927, is owned and operated by Salt River Project. It utilizes conventional hydroelectric and pumped storage technologies, and is considered a hybrid plant. The facility has four generators and its primary fuel source is water (WAT).
In the most recent year of reported data, Horse Mesa generated 87,872 MWh of electricity, achieving a capacity factor of 7.6%. The plant operates within the Salt River Project balancing authority and the Western Electricity Coordinating Council (WECC) NERC region. Horse Mesa is ranked as the 4th largest hydroelectric plant out of 4 in Arizona, and 147th out of 194 nationally.
Generated from EIA, GEM, and public data sources
Engineering & Generators
Grid Context
NERC Region
WECC
Balancing Authority
Salt River Project
Grid Voltage
115 kV
Regulatory Status
RE
Entity Type
Political Subdivision
Sector
Electric Utility
Generation
242 MWh
Net Discharge
87.9K MWh
Annual Net Energy
7.6%
Capacity Factor
Jan 2023 – Dec 2025
Positive values indicate net discharge (generation exceeds station load). Negative values indicate net charging. Pure battery storage plants are typically net negative due to round-trip efficiency losses.
Financial Data
No financial data available for this plant.
Pricing & Market Data
This plant is outside organized wholesale electricity markets (ISOs/RTOs). Nodal pricing data is not available.
News & Articles (10)Beta
Industry·corporate
Salt River Project completes hydropower modernisation, improves efficiency and reliability
Salt River Project (SRP) has completed a multi-year upgrade of its hydroelectric facilities along the Salt River in Arizona.
Salt River Project (operator)
International Water Power·5 months ago
Industry·corporate
Salt River Project, Emerson Complete Hydropower Modernization Project
Industrial technology group Emerson said the company has completed a multi-year modernization project at four hydroelectric dams along the...
Salt River Project (operator)Emerson (other)
POWER Magazine·5 months ago
Industry·technology
Hydroelectricity shows promise to power EV charging stations
Arizona is becoming EV country. With nearly 90,000 electric vehicles registered there, it's among the top 10 states for EV ownership in the...
USA Today·10 months ago
Industry·corporate
How SRP's planned new reservoir in Arizona would work like a 'giant battery'
Salt River Project hopes to generate a lot of clean energy by releasing water from a new reservoir to generate power, then pumping the water...
Salt River Project (developer)
The Arizona Republic·10 months ago
Last updated 2026-03-14
View all 10 articles