Cedar Falls Water Supply
47 25 09.2 N, 121 46 54.4 W
Requests for public power in Seattle began in the late 1890s and lead to the voter approval for building the Cedar Falls Water Supply hydroelectric dam plant in 1902. The first municipally developed and owned hydroelectric plant in the United States began operation in October 1904. The facility is situated one-half mile below Cedar Lake (later known as Chester Morse Lake) near North Bend in King County.
Funding for the power plant came from the sale of municipal bonds, an unusual revenue resource at that time. Once the plant began electrical service, demand rapidly exceeded capacity. As a result, the plant was expanded in 1906, 1908, and 1910. These improvements increased capacity to 40,000 kilowatts. The facility has been modified repeatedly through the years but continues to serve Seattle and surrounding areas.
- The original project, constructed between 1902 and 1904, consisted of a rock-filled, timber crib diversion dam located one-half mile downstream from the outlet of Cedar Lake. The system included a three-mile-long wood stave and two steel penstocks (78-inch pipe) carrying water to two generating units located in a wood-framed powerhouse.
- The turbines were 2,000 hp Pelton impulse wheels that drove two 1,200 kW three-phase AC generators. A 37-mile-long transmission line was constructed to Seattle, designed to supply a voltage of 45kV, the highest transmission voltage in the United States at the time.