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 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. 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.

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. The gross storage capacity is 41,877 acre-feet (51,655,000 m) and the usable (active) storage is 14,443 acre-feet (17,815,000 m).

The lake level changes on a weekly basis with greater drawdowns during the weekdays for power generation, and refilling on the weekends. 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.

Construction was completed in 1925 (100 years ago) (1925).

• List of dams and reservoirs in California