On January 10, 1905, the Cedar Falls hydroelectric plant begins lighting Seattle street lamps for the first time. The plant had begun operation in October 1904. The City of Seattle owns the power plant, which is the first municipally owned plant in the United States.
In 1902, Seattle City Council and the city’s voters approved building the hydroelectric dam plant located one-half mile below Cedar Lake (renamed Chester Morse Lake).
Construction of the dam was an immense undertaking. For example, an enormous amount of lumber was needed and timber company bids to supply the necessary lumber came in too high. Seattle City Engineer R. H. Thomson (1856-1949) decided the city could supply its own lumber by building a sawmill. After extending the railroad tracks three miles up the Cedar River valley, sawmill machinery and equipment was hauled to the site, the mill constructed, and about 2,000,000 board feet of lumber cut.
In June 1902, Thomson hired J. D. Ross (1872-1939) to oversee the installation of the electrical generating equipment. Ross would later head Seattle City Light.
On October 14, 1904, R. H. Thomson and Seattle Mayor Richard Ballinger started up the generators at the Cedar Falls plant. Three months later, on January 10, 1905, the 2,400-kilowatt plant started supplying power to Seattle’s street lights.
The first street lights of Seattle were hanging lights. These "electric arcs" were commonly used in downtown streets during the first decades of the twentieth century. By the 1920s, lampposts had replaced electric arcs.
Calls for a public power system to supply electricity to city residents and businesses, first made in the 1890s, became a reality in September 1905. Demands for electricity quickly exceeded the small plant and in 1906, 1908, and 1910, Seattle voters approved a total of $2,800,000 in bond issues to expand plant capacity and to expand the areas of the city served. Improvements enabled the capacity of the power plant to increase to 40,000 kilowatts.
Before Seattle began supplying power to city residents, the private firm Seattle Electric Company (renamed Puget Sound Power and Light) supplied electricity to residents for 20 cents per kilowatt hour. Within a year after Seattle's Cedar Falls plant began operating, the Seattle Electric Company cut its rate in half.
In 1910, the city's electrical section was transferred from the Water Department to a new city department named Seattle City Light.