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Edward Hyatt Powerplant

Hyatt Powerplant
Hyatt Powerplant was constructed in the bedrock below Lake Oroville. A cavern the size of two football fields was dug out to house the facility. Of the six units, three can pump water or generate power.
(click the image for a larger view)

Located in rock in the left abutment near the axis of Oroville Dam, Edward Hyatt Powerplant is an underground, hydroelectric, pumping-generating facility. Construction of the plant began in 1964 and was completed in 1967.

Hyatt Powerplant maximizes power production through a pumped-storage operation where water, released for power in excess of local and downstream requirements, is returned to storage in Lake Oroville during off-peak periods and is used for generation during peak power demands.

Water from the lake is conveyed to the units through penstocks and branch lines. After passing through the units, water is discharged through the draft tubes to one free surface and one full-flow tailrace tunnel.

The facility was named for Edward Hyatt, who was State Engineer (1927-1950) of the Division of Water Resources under the Department of Public Works. The Division was the predecessor to the Department of Water Resources


Installed Capacity 5,610 cfs, 519,000 cfs
Normal Static Head 500-660 feet
Design Dynamic Head 592 feet
Number of Units 3 (p/g)
Unit Size 1,870 cfs, 173,000 hp


Installed Capacity 819 mVA, 16,950 cfs
Normal Static Head 410-676 feet
Design Dynamic Head: 615 feet
Number of Units 6 (3 g, 3 p/g)
Unit Size: 3 @ 132 mVA, 2,800 cfs
3 @ 141 mVA , 2,850 cfs
Penstock/Diameter 2 @ 22 feet