During 2001, Rock Island's Second Powerhouse produced 1,800 gigawatt-hours of power, representing 95% of the Project's total generation for the year.

Under the terms of the Rock Island Settlement Agreement, the District provides spill to improve the survival rate of juvenile salmon passing the Project.

The license was authorized on October 16, 1929, and on January 14, 1930, at the beginning of the Great Depression, construction started on the first dam to span the Columbia River.

There were three main construction periods, each taking place about 20 years apart as the need for low-cost hydroelectric power was paramount in the region.

Development began in January 1930, and the dam, powerhouse, and first four operating units were turned over to Puget Sound Power & Light Company by Stone and Webster Engineering Corporation on February 1, 1933.