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 (5)Beta
Last updated 2026-03-26
View all 5 articles