Pumped Storage Hydro Plants in California
Every operating pumped storage hydro plant in California on EIA-860M for 2026-07: 6 plants, 29 generating units and 3 GW of nameplate capacity across 4 counties, most of it inside CAISO.
As of 2026-07 (inventory dated 2026-07-31) · EIA-860M Preliminary Monthly Electric Generator Inventory · eia.gov/…/july_generator2026.xlsx · eia.gov/…/eia860m
- Plants
- 6
- 29 generating units
- Nameplate capacity
- 3 GW
- Counties
- 4
- Grid operator
- CAISO
- covers most of these plants
Map of pumped storage hydro plants in California
Every one of the 6 plants is drawn at the coordinate EIA files for it.
Loading map…
- Pumped storage · 6
List of pumped storage hydro plants in California
Sort by any column. Capacity is nameplate, summed across every generating unit EIA lists at the site.
| Castaic2 technologies | Los Angeles Department of Water & Power | Los Angeles | 1,682 | 7 | 1972 | Operating |
| Helms Pumped StorageHydroelectric Pumped Storage | Pacific Gas & Electric Co. | Fresno | 1,053 | 3 | 1984 | Operating |
| W R GianelliHydroelectric Pumped Storage | California Dept. of Water Resources | Merced | 424 | 8 | 1967 | Operating |
| J S EastwoodHydroelectric Pumped Storage | Southern California Edison Co | Fresno | 199.8 | 1 | 1987 | Operating |
| Thermalito2 technologies | California Dept. of Water Resources | Butte | 115.1 | 4 | 1968 | Operating |
| ONeillHydroelectric Pumped Storage | U S Bureau of Reclamation | Merced | 25.2 | 6 | 1967 | Operating |
Largest pumped storage hydro plants in California
- 1CastaicLos Angeles County, California1,682 MW
- 2Helms Pumped StorageFresno County, California1,053 MW
- 3W R GianelliMerced County, California424 MW
- 4J S EastwoodFresno County, California199.8 MW
- 5ThermalitoButte County, California115.1 MW
- 6ONeillMerced County, California25.2 MW
Pumped storage hydro plants by county in California
The county EIA files against each plant. It is the fastest way to find the plant nearest a given town.
| County | Plants | Nameplate MW |
|---|---|---|
| Los Angeles | 1 | 1,682 |
| Fresno | 2 | 1,252.8 |
| Merced | 2 | 449.2 |
| Butte | 1 | 115.1 |
Pumped Storage Hydro Plants in California: FAQ
- How many pumped storage hydro plants are in California?
- 6, with 3 GW of nameplate capacity between them, spread over 4 counties. That is the EIA-860M operating count for 2026-07.
- Is there a map of California pumped storage hydro plants?
- Yes — the map above. Each dot is one pumped storage hydro plant, sized by nameplate capacity and placed at the coordinates EIA files for it.
- Which is the largest pumped storage hydro plant in California?
- Castaic, at 2 GW. The table is sorted largest first, so the rest follow it.
- Is there a pumped storage hydro plant near me in California?
- The county roll-up below groups every plant by county, which is the quickest way to find the one closest to a given town.
- Which grid operator runs California's pumped storage hydro plants?
- Most of them sit inside CAISO, according to the balancing-authority code EIA files against each plant. Live conditions for that market are on this site.
- How current is this, and what is left out?
- EIA-860M for 2026-07. Hydroelectric pumped storage. Plants below 1 MW are not surveyed by EIA and so are absent; retirements and additions after 2026-07 arrive with the next monthly release.