Grand Coulee Dam

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Franklin Delano Roosevelt Lake Grand Coulee Dam
Grand Coulee Dam
Grand Coulee Dam
Location: Washington , USA
Tributaries: Columbia River
Drain: Columbia River
Grand Coulee Dam, Washington
Grand Coulee Dam
Coordinates 47 ° 57 '25 "  N , 118 ° 58' 44"  W Coordinates: 47 ° 57 '25 "  N , 118 ° 58' 44"  W.
Data on the structure
Construction time: 1933-1941, 1966-1974
Height above foundation level : 168 m
Building volume: 9 155 942  m³
Crown length: 1 592  m
Power plant output: 6th 809  MW
Data on the reservoir
Water surface 337 km²
Storage space 11,582 million m³
Grand Coulee Dam construction.jpg
Original dam. The left section was demolished in the 1960s to make way for power house No. 3

The Grand Coulee Dam ( English Grand Coulee Dam ) is a dam with a gravity dam and a hydroelectric power plant on the Columbia River in Washington State . Along with the Hoover Dam , it is one of the most famous dams in the USA . The reservoir is called Franklin Delano Roosevelt Lake, after the former American President Franklin Delano Roosevelt , who was President during the planning and construction. It was declared the Lake Roosevelt National Recreation Area in 1946 . The Grand Coulee Dam was added to the List of Historic Civil Engineering Landmarks by the American Society of Civil Engineers in 1997 .

The dam is almost 1.6 km long and 168 m high.


The dam is part of the Columbia Basin Project to irrigate areas on the northwest coast of the Pacific and produce electricity . Excavation of soil on site began in December 1933 as a job creation program under the New Deal programs and was completed at the start of World War II . The original planning provided for a shorter barrier structure that should be increased later if necessary. During the construction work, the design was changed and the dam was raised. Their height was chosen so that the reservoir does not extend further than the Canadian border.

Original structure

When the dam was completed in 1941, it was the largest dam in the world in terms of the volume of the structure. In the meantime, the purpose of irrigation had become subordinate, because the war mainly needed energy. Aluminum had to be produced for war production , which requires a lot of electricity. The electricity was also used to power the plutonium production reactors and facilities at the Hanford Site , part of the secret Manhattan atomic bomb production project . The dam was important for the industrial development of the northwestern Pacific coast .

The original aim of irrigation was resumed after the war. A water distribution network was built using an old river bed (the "Grand Coulee") that was 200 m above the Columbia River . Further dams, pumping stations, possibly also culverts or siphons , crossings and canals were built and a huge supply network was built. Irrigation started in 1951.


Between 1966 and 1974 the dam was expanded to include power house No. 3. This involved blasting away the north-western side of the dam and building a new section with an enlarged reservoir. This made the dam wall longer and could accommodate six new machine units. The new turbines and generators (three times 600 MW and three times 805 MW) are among the largest ever built. The expansion was completed in the 1980s. This made the Grand Coulee Dam one of the largest hydropower plants in the world. The bottleneck output is given as 6,809 megawatts , but elsewhere also as 6,180 or 6,495 MW. Even 10,830 MW should be planned.

Impact on the environment

The dam has negative consequences for the local Indian tribes, whose traditional way of life revolved around catching salmon, for example at the now flooded Kettle Falls as an important salmon fishing site. The Grand Coulee Dam and the Chief Joseph Dam permanently block the migration of freshwater spawners and deprive them of more than a thousand miles of their previous spawning grounds. The Colville Indian tribe lived on the Columbia River and their land was flooded by the reservoir, causing them to move away. The impact of the dam put an end to the traditional way of life of the indigenous people. They sued the government, which compensated the Colville Indians in the 1990s with a lump sum compensation of around $ 52 million.

Panoramic view of the dam towards the southeast. Powerhouse No. 3 at the lower left end of the dam is large enough to hold five American football fields. In the picture below the Grand Coulee Bridge .

Visits to the dam

In the visitor center there are many historical photos, geological rock samples, models of the turbines and the dam as well as a well-attended theater. Since 1989 a laser light show has been projected onto the dam on summer evenings. The show includes full-size images of battleships and the Statue of Liberty as well as some notes on the environmental impact. Tours in the new power house No. 3 are open to the public but have been restricted for safety reasons. Visitors can take a glass elevator from the gate valve of the pressure pipeline up to a depth of 120 m, where the generators are.

More facts

  • Largest concrete dam in North America, largest concrete structure in the USA with 9.155942 million m³
  • Hydraulic fall height : 116 m
  • Average discharge: 3100 m³ / s
  • 4 power plants, 33 generators, standard energy capacity : 21,000 GWh annually
  • Turbines used: Francis turbines
  • Largest hydropower plant in the USA, currently fifth largest in the world
  • Over 2,000 km² are irrigated
  • On June 1, 1942, the first water flowed over the flood relief
  • Owner and operator: Bureau of Reclamation

Quotes about the Grand Coulee Dam

“Now the world holds seven wonders that the travelers always tell,
Some gardens and some towers, I guess you know them well.
But now the greatest wonder is in Uncle Sam's fair land,
It's the big Columbia River and the big Grand Coulee Dam. [...] ”

- Woody Guthrie : The Grand Coulee Dam

See also

Web links

Commons : Grand Coulee Dam  - Collection of Images, Videos, and Audio Files