The story of the Washington Public Power Supply System is a tale of modest beginnings and grandiose schemes. The organization that took on the task of building five large nuclear power plants had more than a decade's history as a somewhat marginal actor on the Pacific Northwest utility stage. Small though it was at first, the Supply System was ambitious, and its aspirations jibed with the region's perceived energy needs. During the years 1968–73, the Supply System undertook its first three plants under a complex set of arrangements linking the projects to the BPA's Hydro-Thermal Power Program.

The Supply System's institutional origins reflect the skirmishes between public and private power interests in the state of Washington during the 1950s. With the Eisenhower administration's aversion to new Federal hydropower projects, Northwest utilities jockeyed for control of dam sites and for assured access to the kilowatts that new projects could generate. To coordinate power development in Washington, the state legislature established a Washington State Power Commission in 1953. The five-person Commission included three representatives from public utilities and two from the state's investor-owned firms, Washington Water Power and Puget Sound Power & Light. The legislation also permitted two or more municipalities and public utility districts to form new power agencies. These joint agencies could, with the Commission's approval, build and operate generating and transmission facilities.