Edward C Hyatt
California Department of Water ResourcesButte County
Edward C Hyatt is a battery energy storage facility with 644.1 MW of EIA-reported nameplate capacity in Butte County, California, registered as EIA Plant ID 437. California Department of Water Resources is the public owner or developer; California Dept. of Water Resources is the registered plant entity or operator. The Oroville pumped-storage scheme was the first such facility constructed in California and was described by the California Department of Water Resources as one of the largest in the United States. Edward Hyatt Powerplant was also identified as the largest underground powerplant in the United States and received the American Society of Civil Engineers’ 1969 Outstanding Engineering Achievement recognition.
Mapped infrastructure geometry associated with this asset.
Conventional Hydroelectric, Hydroelectric Pumped Storage
Edward C Hyatt is operating.
230 kV · Pacific Gas and Electric Company
CAISO
EIA plant 437 · Inventory for Sep 2026.
| Generator | Technology | Status | Power (MW) | Energy (MWh) |
|---|---|---|---|---|
| 1 | Conventional Hydroelectric | Operating | 117 | Unknown |
| 2 | Hydroelectric Pumped Storage | Operating | 97.7 | Unknown |
| 3 | Conventional Hydroelectric | Operating | 117 | Unknown |
| 4 | Hydroelectric Pumped Storage | Operating | 97.7 | Unknown |
| 5 | Conventional Hydroelectric |
Similar plants ranked by technology, capacity, and distance.
Current generator records and technology attributes reported through EIA-860.
| Generator | Capacity | Technology | Operation | Status |
|---|---|---|---|---|
| 1 | 117 MW 135.3 MW summer | Conventional Hydroelectric HY | Mar 1968 | Operating |
| 2 | 97.7 MW 112.4 MW summer | Hydroelectric Pumped Storage PS | Nov 1968 | Operating |
| 3 | 117 MW 135.3 MW summer | Conventional Hydroelectric HY | Jun 1968 | Operating |
| 4 | 97.7 MW 112.4 MW summer | Hydroelectric Pumped Storage PS | Dec 1968 | Operating |
| 5 | 117 MW 135.3 MW summer | |||
Monthly EIA generation history and recent market-resource behavior where linked telemetry is available.
Deterministic links to ERCOT market resources, price records, outage disclosures, queue records, and nearby infrastructure. Candidate joins remain labeled until corroborated.
Source-backed project transactions, agreements, land records, permits, and environmental disclosures. Portfolio and adjacent-project facts remain explicitly scoped.
Parties, market resources, and identifiers tied to this asset, with owner, operator, developer, EPC, compliance provider, and interconnecting entity roles kept separate.
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Project milestones and public references behind the asset profile.
Excavation and construction began for the underground Hyatt Powerplant at Oroville.
CAISO · Butte County
| Operating |
| 117 |
| Unknown |
| 6 | Hydroelectric Pumped Storage | Operating | 97.7 | Unknown |
|---|
Monthly generation is reported through EIA-923. Capacity factor uses the current EIA nameplate capacity and is shown only for complete calendar years.
| Largest reported plants | Capacity | State | |
|---|---|---|---|
| Edward C HyattCurrent | 644.1 MW | CA | |
| W R Gianelli | 424 MW | CA | |
| Devil Canyon | 276.2 MW | CA | |
| Thermalito | 115.1 MW | CA | |
| W E Warne | 74.2 MW | CA | |
| Mojave Siphon | 32.7 MW | CA | |
| Alamo | 19.6 MW | CA | |
| Thermalito Diverson Dam | 3.4 MW | CA |
Portfolio membership follows the latest EIA-860 reporting entity. It does not imply ultimate ownership.
View full reporting portfolioDWR’s State Water Project development timeline records completion of the Hyatt Powerplant in 1967.
EIA-860 lists generator 1 with this operating date.
EIA-860 lists generator 3 with this operating date.
EIA-860 lists generator 5 with this operating date.
EIA-860 lists generator 2 with this operating date.
EIA-860 lists generator 4 with this operating date.
EIA-860 lists generator 6 with this operating date.
DWR filed a CEQA notice for refurbishment of Units 2, 4, and 6, including replacement of turbine runners, wicket gates, wear rings, and related appurtenances. The notice classified the work as modernization without expansion.
DWR took Hyatt Powerplant offline because of historically low Lake Oroville levels during the statewide drought.
DWR announced resumed hydropower generation, initially using one generating unit and supplying power to the California Independent System Operator-managed grid after completing major maintenance while the plant was offline.
Answered from the published record above. Questions whose inputs this profile does not carry are omitted rather than estimated.
Edward C Hyatt reports 644.1 MW hydroelectric of operating nameplate capacity. These technology ratings do not establish a common export limit. Source: EIA Sep 2026.
Edward C Hyatt is a Conventional Hydroelectric, Hydroelectric Pumped Storage facility in Butte County, CA, participating in the CAISO market.
Edward C Hyatt is in Butte County, CA, inside the CAISO balancing area.
Edward C Hyatt is operated by California Dept. of Water Resources according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.
Edward C Hyatt reported 2,107.7 GWh over the twelve months to 2026-07. Figures are net generation as filed to EIA-923.
Edward C Hyatt interconnects at 230 kV bus of the Table Mountain substation, on the Pacific Gas and Electric Company system.
By capacity, Edward C Hyatt ranks #39 of 1,356 operating plants of the same technology nationally. It ranks #2 of 210 in CA.
Plants within 25 km, nearest first, regardless of technology. Proximity is straight-line distance between mapped plant coordinates; it does not by itself establish a shared point of interconnection.
