Grand Coulee Dam

Grand Coulee Dam

Grand Coulee Dam, 550 ft (168 m) high and 4,173 ft (1,272 m) long, on the Columbia River, N central Wash., NW of Spokane; built 1933-42 as a key unit in the Columbia basin project of the U.S. Bureau of Reclamation. Grand Coulee Dam, one of the world's largest concrete dams, is used for flood control, river navigation, irrigation, and power production that services the varied manufacturing in the area. The dam has the largest power-producing capacity (6,465 MW) in the United States. The dam impounds Franklin D. Roosevelt Lake, 130 sq mi (337 sq km), which extends to the Canadian border; it is one of the largest reservoirs in the United States. Power generated at the dam is used to pump water into Grand Coulee, a vertical-walled gorge, c.30 mi (48 km) long, carved by the Columbia River through the Columbia Plateau. The coulee, dammed at each end, is used as a reservoir (Banks Lake); it supplies water to more than 500,000 acres (202,343 hectares) on the plateau and acts as a backup against pump and power failures. Franklin D. Roosevelt Lake is part of Lake Roosevelt National Recreation Area. Located on the Pacific flyway, a chief north-south migratory route, the area has a great variety of waterfowl and land birds. Grand Coulee (1990 pop. 984) and Coulee Dam (1990 pop. 1,087) were founded by the U.S. government in 1935-36 as construction, operational, and housing bases for the dam.

See L. V. Downs, The Mightiest of Them All (rev. ed. 1993); P. C. Pitzer, Grand Coulee (1995).

Grand Coulee Dam is a hydroelectric gravity dam on the Columbia River in the U.S. state of Washington. In the United States, it is the largest electric power producing facility and the largest concrete structure. It is the fourth largest producer of hydroelectricity in the world. The top producing dams are the Three Gorges Dam in China, the Guri Dam in Venezuela, and the Itaipu Dam on the border of Paraguay and Brazil.

The reservoir is called Franklin Delano Roosevelt Lake, named after the United States President who presided over the completion of the dam. The foundation was built by the MWAK Company, a joint effort of several contractors united for this purpose. Consolidated Builders Incorporated, including industrialist Henry J. Kaiser, completed the dam. The United States Bureau of Reclamation supervised the contractors and operates the dam. Folk singer Woody Guthrie was commissioned by the Bonneville Power Administration to write songs about the Columbia Basin Project; the songs Roll On Columbia and Grand Coulee Dam are part of that series.

The Grand Coulee Dam is almost a mile long at 5223 feet (1586 m). The spillway is 1,650 feet(503 m) wide. At 550 feet (168 m), it is taller than the Great Pyramid of Giza; all the pyramids at Giza could fit within its base. Its hydraulic height of 380 feet (115 m) is more than twice that of Niagara Falls. There is enough concrete to build a four-foot wide, four-inch deep sidewalk twice around the equator.


The dam was built under the auspices of the U.S. Bureau of Reclamation as part of the Columbia Basin Project for irrigation of desert areas of the Pacific Northwest and for the production of electricity. Central Washington's Columbia Basin was a slightly over-ambitious candidate for a dam. The Columbia was by far the largest river anyone had ever considered damming. A Spokane group wanted a safer 134-mile (216 km) gravity flow canal from the Pend Oreille River at Albeni Falls. And the original low dam design would have have been useful for regulating navigation flows, and for hydroelectic power, but it would have been too far below the top of the canyon to make it useful for irrigation of the fertile loess soil of the basin. The controvery over which project should go forward was a central issue of Washington state politics in the 1920s.

By the 1930s, after thirteen years of debate and several studies, and with the Depression in full swing, Roosevelt was eager for large public works. In 1933, President Franklin D. Roosevelt authorized the dam as a Public Works Administration project, and Congress appropriated funding for the low dam. Two years, and endless political machinations. later, the authorization was changed from the low dam, to the far more expensive, and technically challenging, high dam of today.


Excavation of the site began on July 16, 1933. The initial construction plan was for a shorter dam with one partial completed powerhouse with available expansion from 6 units to 18. During construction, the design was changed to the higher specification in order to employ more people, generate more electricity, and to enlarge the irrigation capacity. Construction was completed in January 1942, soon after the U.S. entered WWII. A total of 77 men died. Its height is 1330 feet above sea level at the roadway, the reservoir height is measured when water reaches the top of the drumgates which is 1290 feet above sea level (10 feet below the roadway). The dam was designed by John L. Savage with Frank A. Banks as chief construction engineer. For several years it was the largest producer of hydroelectricity in the world.

The primary goal of irrigation was postponed as the wartime need for electricity increased. Aluminum smelting was vital to the war effort, and to airplane construction in particular. The electricity was also used to power plutonium production reactors and reprocessing facilities at the Hanford Site, which was part of the then top-secret Manhattan Project.

The dam was instrumental in the industrial development of the Pacific Northwest.


The original goal of irrigation resumed after the war. A water distribution network was built using the adjacent Grand Coulee to hold the main reservoir now known as Banks Lake. Additional dams, siphons, and canals were constructed, creating a vast irrigation supply network called the Columbia Basin Project. Irrigation began in 1951.

Water is pumped up 280 feet (85 m) from Lake Roosevelt to Banks Lake using twelve 14-foot-wide pipes. Pumped-storage hydroelectricity capability was incorporated into the final six pumps. During low-demand periods, water is pumped into Banks Lake, to be used later during high-demand periods. Water flow is reversed, powering generators as it falls back into Lake Roosevelt. This function is used regularly when irrigation water demand is low and electricity demand is high.


Between 1966 and 1974 the dam was expanded to add the Third Powerhouse. This involved demolishing the northeast side of the dam and building a new forebay section. The addition made the dam more than a mile long and accommodated six new generators. Original designs for the powerhouse had twelve smaller units but was changed to incorporate the largest units available. The new turbines and generators, three 600 MW and three 805 MW units, are today nearly the largest ever produced. The expansion was completed in the early eighties and made the Grand Coulee Dam once again one of the largest hydroelectric producers in the world.

The expansion of the dam also required the installation of over 20 km of oil-cooled cables. These 6" cables, made in Japan by Sumitomo Electric, are rated to a maximum potential of 525 kV and are connected to powerful pumps which circulate the oil through the cables during normal operation.

Environmental and cultural consequences

The dam had negative consequences for the local Native American tribes whose traditional way of life revolved around salmon. Grand Coulee Dam and nearby Chief Joseph Dam (built in 1953) permanently block anadromous fish, removing over a thousand miles of their traditional spawning grounds. The various confederated tribes of the Colville Indian Reservation live along the Columbia River. Grand Coulee Dam flooded over 21,000 acres (85 km²) of prime bottom land where Indians had been living for thousands of years, forcing the relocation of settlements and graveyards. The ancient and important salmon fishing site at Kettle Falls was inundated. The town of Kettle Falls, Washington was relocated. The environmental impact of the dam effectively ended the traditional way of life of the native inhabitants, who sued the government. The government eventually compensated the Colville Indians in the 1990s with a lump settlement of approximately $52 million, plus annual payments of approximately $15 million.
The architects of the new [Columbia] river have been nearly constant in their protestations of concern for salmon, but they have quite consciously made a choice against the conditions that produce salmon. They have wanted the river and its watershed to say electricity, lumber, cattle, and fruit and together these have translated into carp, shad, and squawfish instead of salmon. If ever a death could be unintended and overdetermined, it is the death of the wild runs of the Columbia River salmon. - Richard White

Touring the dam

The visitor center contains many historical photos, geological samples, turbine and dam models, and a well used theater. Since 1989, on summer evenings, The laser light show at Grand Coulee Dam is projected onto the dam's wall. The show includes full-size images of battleships and the Statue of Liberty, as well as some environmental comments. Tours of the new Third Powerhouse are available to the public but have been scaled back for security reasons. Visitors are able to ride a glass elevator, on top of the forebay penstocks, 400 feet down to view the generators.


  • Largest concrete dam and concrete structure in North America with 11,975,521 yd³ (9,155,942 m³) used]]
  • Total length of dam: 5,223 ft (1,592 m)
  • Length of main dam: 3,867 ft (1,178 m)
  • Length of forebay dam: 1,170 ft (356 m)
  • Length of Wing Dam: 186 ft (56 m)
  • Hydraulic height: 380 ft (116 m)
  • Height of dam from bedrock: 550 ft (168 m)
  • Height above original streambed: 401 ft (122 m)
  • Reservoir Lake Roosevelt stretches for 151 mi (243 km)
  • Average release: 110,000 ft³/s (3,100 m³/s)
  • 4 power plants, 33 generators
  • Installed generating capacity: 6809 MW



  • Ray Bottenberg: Grand Coulee Dam (Charleston, SC: Arcadia Publishing, 2008).
  • J. Harlen Brentz: The Grand Coulee (American Geographical Society, 1932).
  • L. Vaughn Downs: The Mightiest of Them All: Memories of Grand Coulee Dam (American Society of Civil Engineers, 1993).
  • Marcia S. Gresko: The Grand Coulee Dam (Blackbirch Press, 1999).
  • Paul C. Pitzer: Grand Coulee: Harnessing a Dream (Pullman: Washington State UP, 1994).
  • George Sundborg: Hail Columbia: The Thirty-year Struggle for Grand Coulee Dam (New York: Macmillan, 1954).
  • Richard White: The Organic Machine: The Remaking of the Columbia River (New York: Hill and Wang, 1995).

External links

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