Grand Coulee Dam Grand Coulee Dam Grand Coulee Dam is a concrete gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. Constructed between 1933 and 1942, Grand Coulee originally had only two powerhouses. The third powerhouse, completed in 1974 to increase energy production, makes Grand Coulee the largest power station in the United States by nameplate-capacity at 6,809 MW. However, in terms of yearly power production, Grand Coulee places fifth after a number of nuclear facilities to the south, like Palo Verde west of Phoenix, as the river flow varies throughout
Grand Coulee Dam in the newspapers, stating exploratory drilling at the Grand Coulee site found no granite on which a dam's foundations could rest, only clay and fragmented rock. This was later disproved with Reclamation-ordered drilling. Ditchers hired General George W. Goethals, engineer of the Panama Canal, to prepare a report. Goethals visited the state and produced a report backing the ditchers. The Bureau of Reclamation was unimpressed by Goethals' report, believing it filled with errors. In , President Warren G. Harding visited Washington state and expressed support for irrigation work there, but died a month later. His successor, Calvin Coolidge, had little