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Grand Coulee Dam
Creates	Franklin Delano Roosevelt Lake Banks Lake
Locale	Grand Coulee, Washington
Maintained by	U.S. Bureau of Reclamation
Length	5,223 ft (1592 m)[1]
Height	550 ft (168 m)
Opening date	June 1, 1942
Geographical Data
Coordinates	47°57.4′N 118°59′WCoordinates: 47°57.4′N 118°59′W

Grand Coulee Dam is a hydroelectric gravity dam on the Columbia River in the U.S. state of Washington. It is the largest electric power producing facility^[3] and the largest concrete structure in the United States.^[4]

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 song Grand Coulee Dam is one of that series.

The Grand Coulee Dam is almost a mile long. It is taller than the Great Pyramid of Giza; all the pyramids at Giza could fit within its base. It is more than twice as tall as Niagara Falls.

The dam was built as part of the Columbia Basin Project for irrigation of desert areas of the Pacific Northwest and for the production of electricity.^[5] Excavation of the site began in December of 1933 as a public works project and finished toward the beginning of WWII. 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 and enlarge the irrigation capacity. Its height is 1330 above sea level at the roadway, the reservoir height is measured when water reaches the top of the drumgates which is 1,290 ft above sea level (10 feet below the roadway).^[6]

Construction of the original dam. The left section would be blown up in the late sixties to make way for powerhouse #3

One of six new Francis turbines, rated at nearly one million hp, being installed in powerhouse #3.

The primary goal of irrigation was postponed as the war time 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.

Because of the critical importance of the constant supply of electrical power to the Hanford plutonium production facility, a Pumped-storage hydroelectricity capability was added to the dam so that if the main powerhouse were incapacitated (i.e. by enemy attack, such as the Japanese Fire balloon), backup power could be provided by the pump/generators that, instead of pushing water to Banks Lake in pumping from the pump, would reverse and become a generator from the falling water. This function has been used every year when the irrigation reservoir is drawn down in the winter.

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

The original goal of irrigation resumed after the war. A distribution network for water was built using the Grand Coulee, a dry canyon-like former Columbia River bed coulee whose rim is 1,600 feet (200 m) above the undammed height of the Columbia river, as the main reservoir. Additional dams, siphons, and canals were constructed, creating a vast irrigation supply network called the Columbia Basin Project. The water-filled lake in Grand Coulee is called Banks Lake.

Irrigation began in 1951.^[6]

The interior of powerhouse #3. Also pictured is the worlds largest indoor crane

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 keep the number one slot. The new turbines and generators, three 600 MW and three 805 MW units, are some of the largest ever produced. The expansion was completed in the early eighties and made the Grand Coulee Dam 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.

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,^[7] 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.^[8] The ancient and important salmon fishing site at Kettle Falls was inundated. The town of Kettle Falls 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.

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.

Panoramic view of the dam, looking Southeast. Powerhouse number three, visible at the lower left of the dam, is large enough to hold five football fields end to end.

An 87.5 kg (192.9 lb) nut and bolt, one of sixteen used to join sections of the generator shaft of a 75000 kW generator at Grand Coulee Dam in 1942

• Largest concrete dam in North America, largest concrete structure in the United States with 11,975,521 yd³ (9,155,942 m³) used^{[citation needed]}
• Hydraulic Height: 380 ft (116 m)
• Height of Dam from Bedrock: 550 ft
• Reservoir Lake Roosevelt stretches for 151 mi
• Average release: 110,000 ft³/s (3,100 m³/s)
• 4 power plants, 33 generators
• Installed generating capacity: 6809 MW ^[9]

• Paul C. Pitzer: Grand Coulee: Harnessing a Dream (Pullman: Washington State UP, 1994).
• Richard White: The Organic Machine: The Remaking of the Columbia River (New York: Hill and Wang, 1995)

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Grand Coulee Dam

• Official web site - U.S. Bureau of Reclamation
• GrandCouleeDam.org Informational web site
• Grand Coulee Dam Columbia Basin Project Historical site Personal interest site maintained by Charles Hubbard
• University of Washington Libraries Digital Collections – Grand Coulee Dam Photographs and pamphlets of the construction of the dam. Includes information about the recommendations for and against building the dam as well as images of land clearing activities by the Public Works Administration.
• Central Washington University Library Digital Collections The Rufus Woods Photograph Collection contains photographic prints and negatives of the Grand Coulee Dam in Washington State prior to, during and after construction. The photographs visually document the construction of the dam, the conditions in the Columbia River Basin throughout construction and the introduction of irrigation in north central Washington State