Grand Coulee Dam and completion. Creation of the reservoir forced the relocation of over 3,000 people, including Native Americans whose ancestral lands were partially flooded. While the dam does not contain fish passage, neither does the next downstream dam, Chief Joseph Dam. This means no salmon reach the Grand Coulee Dam. The second large dam downstream, Rocky Reach Dam, has an intricate system of fish ladders to accommodate yearly salmon spawning and migration. The Grand Coulee is an ancient river bed on the Columbia Plateau created during the Pliocene Epoch (Calabrian) by retreating glaciers and floods. Originally, geologists believed a glacier that diverted
Grand Coulee Dam interest in irrigation projects. The Bureau of Reclamation, desirous of a major project that would bolster its reputation, was focusing on the Boulder Canyon Project that resulted in the Hoover Dam. Reclamation was authorized to conduct a study in 1923, but the project's cost made federal officials reluctant. The Washington state proposals received little support from those further east, who feared the irrigation would result in more crops, depressing prices. With President Coolidge opposed to the project, bills to appropriate money for surveys of the Grand Coulee site failed. In 1925, Congress authorized a U.S. Army Corps of Engineers study