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 of Lower Grand Coulee. The Great Cataract forms the divide from the upper to lower coulees. The Lower Coulee tends along the monoclinal flexure to Soap Lake where the canyons end and the water flowed out into Quincy Basin. Quincy Basin is filled with the eroded gravels and silts from the Coulee. The Lower Coulee, also created its own path across the plains. Evidence of this is found in the tilted flows visible at Hogback islands in Lake Lenore and tilted flows along Washington 17 from Dry Falls to Park Lake. Numerous canyons acted as a distribution system for the