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Thermalito Facilities

diversion dam
The Dam diverts water in the Canal for power generation at Thermalito Pumping Generating Plant. Recreationists can use the Diversion Pool for non-motor boating, fishing, and swimming.
(click the image for a larger view)

Thermalito Diversion Dam and Pool

Constructed between 1963 and 1968, the Thermalito Diversion Dam and Pool are located on the Feather River, about 4.5 miles downstream from Oroville Dam.

The dam diverts water in Thermalito Power Canal for power generation at Thermalito Pumping Generating Plant and creates a tailwater pool for Hyatt Powerplant.

The reservoir also acts as a forebay when Hyatt Powerplant is pumping water back into Lake Oroville. It also provides recreation opportunities.

Dam

Type concrete gravity
Embankment volume 154,000 cubic yards
Height 143 feet
Crest length 1,300 feet
Crest elevation 233 feet

Pool

Maximum operating storage (mos) 13,350 acre-feet
Water surface elevation @ mos 225 feet
Water surface area @ mos 320 acres
Shoreline @ mos 10 miles

Thermalito Diversion Dam Powerplant

Thermalito Diversion Dam Powerplant is located at Thermalito Diversion Dam below the left abutment of the dam. (for photo, see diversion dam)

The powerplant generates electricity from water released to the Feather River to maintain fish habitat between the diversion dam and Thermalito Afterbay river outlet. It was constructed between 1985 and 1987.

Generating

Installed capacity 3.3 MVA, 615 cfs
Normal static head 63 - 77 feet
Design dynamic head 67 feet
Number of units 1
Unit size 3.3 mVA, 615 cf
Discharge lines/diameter 2 @ 5 to 1 @ 7.5

power canal
Water can flow either direction in the Thermalito Power Canal.
(click the image for a larger view)

Thermalito Power Canal

The Thermalito Power Canal extends from a headworks structure which is part of Thermalito Diversion Dam to Thermalito Forebay.

It conveys water in either direction between Thermalito Diversion Dam and Thermalito Forebay for pumping and power generation at Hyatt Powerplant and Thermalito Pumping-Generating Plant.

Construction on the canal began in 1965 and was completed in 1967.

Canal

Type concrete-lined
Length 10,000 feet
Maximum generating Flow 16,900 cfs
Maximum pumping flow 9,000 cfs
Water depth  
Side slope 1 1/2:1

forebay
Thermalito Forebay serves an important role in the pumpback operations of the Oroville-Thermalito Complex and offers recreational activities.
(click the image for a larger view)

Thermalito Forebay

Constructed between 1965 and 1968, Thermalito Forebay is an offstream reservoir contained by Thermalito Forebay Dam on the south and east and by Campbell Hills on the north and west. It is located about four miles west of the city of Oroville.

The forebay conveys generating and pumping flows between Thermalito Power Canal and Thermalito Powerplant, provides regulatory storage and surge damping for the Hyatt-Thermalito power complex, and serves as a recreational site.

Dam

Type homogeneous and zoned earthfill
Embankment volume 1,840,000 cubic yards
Height 91 feet
Crest length 15,900 feet
Crest elevation 231 feet

Forebay

Maximum operating storage 11,770 acre-feet
Water surface elevation @ mos 225 feet
Water Surface Area @ mos 630 acres
Shoreline @ mos 10 miles

pumping-generating plant
Thermalito Pumping-Generating Plant is operated in tandem with Hyatt Powerplant and Thermalito Diversion Dam Powerplant in pumpback operations. Three of its four units can pump and generate.
(click the image for a larger view)

Thermalito Pumping-Generating Plant

Located about four miles west of the city of Oroville in Butte County, Thermalito Pumping-Generating Plant is a principal feature of the Oroville-Thermalito pumped storage power complex. A pumping-generating plant, the facility is operated in tandem with Hyatt Powerplant and Thermalito Diversion Dam Powerplant to produce power.

Water released for power in excess of local and downstream requirements is conserved by pumpback operation during off-peak hours through both power plants into Lake Oroville to be subsequently released for power generation during periods of peak power demand. Construction on the plant began in 1964 and was completed in 1969, with operations starting in 1968.

Pumping

Installed capacity 9,120 cfs, 120,000 hp
Normal static head 85-102 feet
Design dynamic head 99 feet
Number of units 3 (p/g)
Unit size 3 @ 3,040 cfs, 40,000 hp

Generating

Installed capacity 120 MVA, 17,400 cfs
Normal static head 85-102 feet
Design dynamic head 95 feet
Number of units 4 (1g, 3 p/g)
Unit size 3 @ 28 MVA (p/g), 4,200 cfs
1 @ 36 MVA (g), 4,800 cfs
Penstock/diameter 1 @ 24 to 21 feet
3 @ 21 to 18 feet

afterbay
Water is released from Thermalito Afterbay into the Feather River. The afterbay also provides a variety of recreational activities.
(click the image for a larger view)

Thermalito Afterbay

Located about six miles southwest of the city of Oroville, Thermalito Afterbay is an offstream reservoir.

The afterbay provides storage for the water required by the pumpback operation to Lake Oroville, helps regulate the power system, produces controlled flow in the Feather River downstream from the Oroville-Thermalito facilities, and provides recreation. It also serves as a warming basin for agricultural water deliver to farms east of the afterbay.

Thermalito Afterbay Dam has the longest crest in the SWP system. The facility was constructed from 1965 to 1968.

Dam

Type homogeneous earthfill
Embankment volume 5,020,000 cubic yards
Height 39 feet
Crest length 42,000 feet
Crest elevation 142 feet

Afterbay

Maximum operating storage: 57,040 acre-feet
Water surface elevation @ mos 136.5 feet
Water surface area @ mos 4,300 acres
Shoreline @ mos 26 miles