The Chief Joseph Dam is a hydroelectric power plant, concrete gravity dam on the Columbia River, 2.4 km (1.5 mi) upriver from Bridgeport, Washington, USA. The Chief Joseph Dam was authorized as Foster Creek Dam and Powerhouse for power generation and irrigation by the River and Harbor Act of 1946. The River and Harbor Act of 1948 renamed the project Chief Joseph Dam in honor of the Nez Perce chief who spent his last years in exile on the Colville Indian Reservation. Like the nearby Grand Coulee Dam, Chief Joseph Dam completely blocks salmon migration on the upper Columbia River.

The Construction of Chief Joseph Dam Hydro electric power plant began in 1949, with the main dam and intake structure completed in 1955. Installation of the initial generating units was completed in 1958. Eleven additional turbines were installed between 1973 and 1979, and the dam and lake were raised 3 m (10 ft), boosting the capacity to 2,620 MW, making Chief Joseph Dam the second largest hydroelectric power producer in the United States.

The Chief Joseph Dam is 877 km (545 mi) upriver from the mouth of the Columbia at Astoria, Oregon. It is operated by the USACE Chief Joseph Dam Project Office, and the electricity is marketed by the Bonneville Power Administration.

Chief Joseph Dam is a run-of-the-river dam which means the lake behind the dam is not able to store large amounts of water. Water flowing to Chief Joseph Dam from Grand Coulee Dam must be passed on to Wells Dam at approximately the same rate. With 27 main generators in the powerhouse, it has the hydraulic capacity of 6,030 m3/s (213,000 cu ft/s).

In the event more water flows to Chief Joseph Dam than could be used for power generation, the spillway gates would be opened to pass the excess water. With an average annual flow rate of 3,058 m3/s (107,992 cu ft/s), the Columbia River seldom exceeds the powerplant’s capability to pass water, and spilling of water is infrequent at Chief Joseph Dam.

The reservoir behind the dam is named Rufus Woods Lake, and runs 82 km (51 mi) up the river channel. Bridgeport State Park, on the lake, is adjacent to the dam.

Chief Joseph Dam
Locale Douglas and Okanogan counties,
United States
Coordinates 47°59′43″N 119°38′00″W / 47.99528°N 119.6333333°W / 47.99528; -119.6333333Coordinates: 47°59′43″N 119°38′00″W / 47.99528°N 119.6333333°W / 47.99528; -119.6333333
Construction began 1949
Opening date 1979
Type of dam Concrete-gravity, run-of-the-river
Length 5,962 ft (1,817 m)
Height 236 ft (72 m)
Base width 164 ft (50 m) Crest:22 ft (7 m)
Impounds Columbia River
Type of spillway Service, gate-controlled
Discharge capacity of spillway 6,030 m3/s (212,947 cu ft/s)
Creates Rufus Woods Lake
Capacity 516,000 acre foot (636,000,000 m3)
Catchment area 75,400 sq mi (195,285 km2)
Surface area 13.1 sq mi (34 km2)
Power station
Operator(s) USACE
Type Yes
Turbines 27 x Francis turbines
Installed capacity 2,620 MW