Southwest Suburban Sewer District (the District) was established in 1945 for the purpose of operating and maintaining the sewer infrastructure installed by the Federal Government during World War II. The District purchased the White Center trunk sewer from the Federal Government in 1954. At the time of incorporation, the District consisted of a 900 acre service area around the White Center community. Through annexations, the District now encompasses approximately a 10 square mile region serving the City of Burien, the City of Normandy Park, portions of the City of Seattle, City of Des Moines, City of Seatac, and a portion of Valley View Sewer District. The system, which is tributary to the District’s two treatment plants includes 288 miles of pipeline within the two drainage basins, the Salmon Creek Drainage Basin to the north and the Miller Creek Drainage Basin to the south.
The District provides wastewater collection and operates two wastewater treatment plants within its service boundary. The Salmon Creek and Miller Creek treatment plants began operation in 1957 and 1967, respectively. Both plants were upgraded in 1972 with the provision of chlorine contact chambers and still providing primary treatment.
In 1985, design began on secondary treatment upgrade. The Miller Creek plant upgrade became operational in 1988, the Salmon Creek upgrade in 1989 and the compost facility in 1990. The final phase, odor scrubbing, of both treatment facilities became operational in November, 1991.
The District administrative office has been located at 431 SW Ambaum Boulevard since its construction in 1964.