Horse Mesa
Maricopa County, Arizona · EIA plant ID 145 · Operator: Salt River Project
Nameplate131MWSummer 149 MW
Generators4in service
Net generation74GWh12 mo to Aug 2026
Capacity factor0%hydro units, summer MW
Heat rate—thermal plants only
First online1927
The 12-month figures include preliminary EIA-923 months, which EIA revises. Final data runs through Dec 2025.
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), hydro units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 230.5 | 19.8% | — |
| 2002 | 107.7 | 26.0% | — |
| 2003 | 231.6 | 14.1% | — |
| 2004 | -5.2 | 11.5% | — |
| 2005 | 63.1 | 10.2% | — |
| 2006 | 102.4 | 13.3% | — |
| 2007 | 64.6 | 5.3% | — |
| 2008 | 52.8 | 7.8% | — |
| 2009 | 120.5 | 14.7% | — |
| 2010 | 145.1 | 13.6% | — |
| 2011 | 73.9 | 11.6% | — |
| 2012 | 98.1 | 32.0% | — |
| 2013 | 41.1 | 20.4% | — |
| 2014 | 15.4 | 12.8% | — |
| 2015 | 41.2 | 4.8% | — |
| 2016 | 45.4 | 15.8% | — |
| 2017 | 21.9 | 9.7% | — |
| 2018 | 50.1 | 11.4% | — |
| 2019 | 41.1 | 1.3% | — |
| 2020 | 52 | 1.6% | — |
| 2021 | 79.5 | 1.6% | — |
| 2022 | 77.7 | 2.4% | — |
| 2023 | 127.6 | 8.2% | — |
| 2024 | 98.4 | 16.6% | — |
| 2025 | 87.9 | 10.6% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| HM1 | Conventional Hydroelectric | HY | 9.9 | 10 | Apr 1927 | Operating | — | coming soon |
| HM2 | Conventional Hydroelectric | HY | 9.9 | 10 | Apr 1927 | Operating | — | coming soon |
| HM3 | Conventional Hydroelectric | HY | 11.7 | 10 | Apr 1927 | Operating (Out of service, expected back within the year) | — | coming soon |
| HM4 | Hydroelectric Pumped Storage | PS | 99.8 | 119 | Jun 1927 | Operating | — | coming soon |
Owner / operator
Operator: Salt River Project. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Salt River Project | 100.0% | 131 MW |
Nearby plants
Within 80 km.
| Mormon Flat | 64 MW | 10.1 km |
| Stewart Mountain | 13 MW | 18 km |
| Roosevelt | 36 MW | 19.1 km |
| Pediment BESS I | 250 MW | 35.4 km |
| Mesa Carport PV | 5 MW | 36.2 km |
| South Consolidated | 1 MW | 42.8 km |