Grand Coulee Dam

Grand Coulee Dam is a gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. It was constructed between 1933 and 1942, originally with only two powerhouses. The third powerhouse, completed in 1974 to increase energy production, makes Grand Coulee the largest electric power-producing facility in the United States.

• http://en.wikipedia.org/wiki/Grand Coulee Dam