Pit 3 Dam

Pit-3 Dam (also known as Pit Number Three Dam and Dam Number Three) is a hydroelectric dam on the Pit River in northern California in the United States. It forms Lake Britton, and is owned by the Pacific Gas and Electric Company (PG&E).

Pit-3 Dam
Satellite view
Location of Pit-3 Dam in California
Official name	Pit Number Three Dam
Country	United States
Location	Shasta County, California
Coordinates	41°01′18″N 121°40′33″W
Owner(s)	Pacific Gas and Electric Company[1]
Dam and spillways
Impounds	Pit River
Height	130 ft (40 m)[2]
Length	494 ft (151 m)[2]
Width (crest)	30 ft (9.1 m)[1]
Width (base)	110 ft (34 m)[1]
Reservoir
Creates	Lake Britton
Total capacity	41,877 acre⋅ft (51,655,000 m3)[2]
Catchment area	4,700 square miles (12,000 km2)[1]
Surface area	1,265 acres (5.12 km2)[3]
Power Station
Type	Run-of-the-river
Hydraulic head	600 feet (180 m)[2]
Installed capacity	69.9 MW[2]
Annual generation	333,606,000 KWh (2001–2012)[4]

Specifications

Pit 3 is a curved concrete gravity dam with a height of 130 ft (40 m) and length of 494 ft (151 m). The dam has a gated spillway with three steel gates and three inflatable rubber gates.^[2]: 6 An intake structure at the dam diverts water into a 19-foot (5.8 m) diameter, 21,203-foot (6,463 m) long tunnel that connects to the Pit 3 hydroelectric plant. There are three 23.3 MW generators, for a total capacity of 69.9 MW.^[2]: 6

Lake Britton, formerly known as Pit 3 Reservoir, has a maximum water level of 2,737.5 ft (834.4 m); however, the lake is usually kept below 2,736.5 ft (834.1 m) to avoid flooding parts of McArthur–Burney Falls Memorial State Park.^[2]: 279 The gross storage capacity is 41,877 acre-feet (51,655,000 m³) and the usable (active) storage is 14,443 acre-feet (17,815,000 m³).^[2]: 6

The lake level changes on a weekly basis with greater drawdowns during the weekdays for power generation, and refilling on the weekends.^[2]: 9 In addition to generating power at the Pit 3 hydroelectric station, the reservoir also helps regulate water flowing through the Pit 4 and Pit 5 stations downstream.

The dam is the place where Pacific Crest Trail crosses the Pit River.^[2]: 279

History

Construction was completed in 1925 (100 years ago) (1925).^[5]

See also

• List of dams and reservoirs in California