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115.1 MW Conventional Hydroelectric (33 MW) + Hydroelectric Pumped Storage (83 MW) operating in Butte, CA — California Independent System Operator
115.1 MW
Nameplate Capacity
4
Generators
units
Hybrid (2)
Technology
Conventional Hydroelectric + Hydroelectric Pumped Storage
1968
Operating Since
Coordinates
39.5149, -121.6301
County
Butte, CA
Nearby Plants
Owner data does not fully agree across sources.
EIA typically reports the operating utility, while GEM resolves to the financial owner or parent corporation. Both can be correct.
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | California Dept. of Water Resources | California Department of Water Resources | — |
| Owner(s) | California Dept. of Water Resources | California Department of Water Resources | — |
| Status | Operating | operating | — |
GEM identifies the owner as California Department of Water Resources
This entity is not yet in the GEM ownership database — chain unavailable.
The Thermalito plant, located in Butte County, California, is a 115.1 MW hybrid hydroelectric pumped storage facility. It began operating in 1968 and is owned and operated by the California Department of Water Resources. The plant utilizes water as its primary fuel source and consists of four generators employing conventional hydroelectric technology.
Thermalito operates within the California Independent System Operator (CAISO) balancing authority and the Western Electricity Coordinating Council (WECC) NERC region. In the most recent year with available data, the plant generated 322,349 MWh, achieving a capacity factor of 32.1%. Thermalito ranks as the 37th largest of 42 plants in California and 164th largest of 194 plants nationally.
Generated from EIA, GEM, and public data sources
ISO/RTO
CAISO
Market
ISO/RTO Member
NERC Region
WECC — Western Electricity Coordinating Council
Balancing Authority
California Independent System Operator (CISO)
Grid Voltage
230.0 kV
Regulatory Status
RE — Regulated
Entity Type
State
Sector
Electric Utility
11.7K MWh
Net Discharge
322.3K MWh
Annual Net Energy
32.1%
Capacity Factor
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.
2013
$2,294/kW
Est. Construction Cost
Total estimated cost: $264.1M
Market Position
ISO/RTO Market
CAISO
LMP Node
THERMLTO_2_N109
Pricing Hub
TH_NP15_GEN-APND
Location Type
Pricing Node
Node Source
Curated node match
Last updated 2026-03-26
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