State Water Project
Information About
 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 |
 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 |
 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 |
 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 |
 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 |