Fort Peck Reservoir

Fort Peck Dam
Aerial view of Fort Peck Dam, looking west. Fort Peck, Montana. 1986
Location of the Fort Peck Dam in Montana
Country	United States
Location	Fort Peck, Montana
Coordinates	48°00′10″N 106°24′58″W / 48.00278°N 106.41611°W / 48.00278; -106.41611Coordinates: 48°00′10″N 106°24′58″W / 48.00278°N 106.41611°W / 48.00278; -106.41611
Construction began	1933 (U.S. Army Corps of Engineers)
Opening date	1940
Construction cost	$100 million
Dam and spillways
Type of dam	Hydraulic earthfill
Impounds	Missouri River
Height	250 ft (76 m)
Length	21,026 ft (6,409 m)
Width (crest)	50 ft (15 m)
Width (base)	3,500 ft (1,100 m)
Dam volume	125,628,000 cu yd (96,049,000 m3)
Spillway type	Controlled overflow, 8x bulkhead gates
Spillway capacity	250,000 cu ft/s (7,100 m3/s)
Reservoir
Creates	Fort Peck Lake
Total capacity	18,463,000 acre·ft (22.774 km3)
Catchment area	57,500 sq mi (149,000 km2)
Surface area	241,000 acres (98,000 ha)
Power station
Hydraulic head	220 ft (67 m)
Turbines	5x vertical Francis turbines
Installed capacity	185 MW
Annual generation	1,048 GWh
Fort Peck Dam
U.S. National Register of Historic Places
Show map of Montana Show map of the US
Location	On the Missouri River, Fort Peck, Montana
Area	500 acres (200 ha)
Built	1933
Architectural style	Art Deco
MPS	Fort Peck MRA
NRHP Reference #	86002061
Added to NRHP	August 13, 1986

The Fort Peck Dam is the highest of six major dams along the Missouri River, located in northeast Montana in the United States, near Glasgow, and adjacent to the community of Fort Peck. At 21,026 feet (6,409 m) in length and over 250 feet (76 m) in height, it is the largest hydraulically filled dam in the United States, and creates Fort Peck Lake, the fifth largest man-made lake in the U.S., more than 130 miles (210 km) long, 200 feet (61 m) deep, and it has a 1,520-mile (2,450 km) shoreline which is longer than the state of California's coastline. It lies within the Charles M. Russell National Wildlife Refuge. The dam and the 134-mile-long (216 km) lake exist for the purposes of hydroelectric power generation, flood control, and water quality management.

The dam presently has a nameplate capacity of 185.25 megawatts, divided among 5 generating units (which in turn are divided between the Western and Eastern grids). Three units in powerhouse number one, completed in 1951, have a capacity of 105 MW. Completed in 1961, the two remaining generating units in powerhouse number 2, have a nameplate capacity of 80 MW.

The lake has a maximum operating pool elevation of 2,250 feet (686 m) above mean sea level and a normal operating pool elevation of 2,246 feet (685 m) above mean sea level. The lake level fluctuates over time based on a number of factors. During the first week of February 2007, the reservoir set a record low elevation of 2,197 feet (670 m) above mean sea level, nearly 12 feet (3.7 m) lower than the previous record low set in 1991. In June 2011, in response to the 2011 Missouri River Floods, the dam was releasing almost 66,000 cubic feet per second (1,900 m³/s), which greatly exceeded its previous record release of 35,000 cu ft/s (990 m³/s) set in 1975.

Fort Peck was a major project of the Public Works Administration, part of the New Deal. Construction of Fort Peck Dam started in 1933, and at its peak in July 1936 employed 10,546 workers. The dam, named for a 19th-century trading post, was completed in 1940, and began generating electricity in July 1943. The town of Fort Peck, Montana, "the government town," was built for Army Corps of Engineers personnel and men in "positions of responsibility" and their families during the dam's construction. Many of the facilities that supported the dam's workers are still utilized today, such as the recreation center and the theater. In addition to Fort Peck, other towns sprang up to house the workers. Among these were Wheeler and McCone City as well as more than a dozen others. Many of the homes were later moved to farms and towns around Montana.