Grand Coulee Dam fish ladder, Grand Coulee Dam permanently blocks fish migration, removing over of natural spawning habitat. By largely eliminating anadromous fish above the Okanogan River, the Grand Coulee Dam also set the stage for the subsequent decision not to provide for fish passage at Chief Joseph Dam (built in 1953). Chinook, Steelhead, Sockeye and Coho salmon (as well as other important species including Lamprey) are now unable to spawn in the reaches of the Upper Columbia Basin. The extinction of the spawning grounds upstream from the dam has prevented the Spokane and other tribes from holding the first salmon ceremony. Grand
Grand Coulee Dam of electricity. Each generator is supplied with water by an individual penstock. The largest of these feed the Third Powerplant and are in diameter and can supply up to . The dam's power facilities originally had an installed capacity of 1,974 MW but expansions and upgrades have increased generation to 6,809 MW installed, 7,079 MW maximum. Grand Coulee Dam generates 21 TWh of electricity annually. This means the dam generates about 2,397 MW of power on average, which results in a total plant factor efficiency of 35%. In 2014, 20.24 TWh of electricity was generated. Grand Coulee Dam's spillway is