Water and Sewer Lines
Because of its role in overseeing or providing water and wastewater services, King County retains certain records, including maps, of water, sewer, and septic systems.
The City of Seattle provides potable water for approximately 1,300,000 people in King County either through direct service or by the sale of water to 27 other water utilities. The remaining King County population obtains its potable water from other public and private systems.
King County provides wholesale wastewater treatment services to cities and local sewer utilities in King, Snohomish and Pierce counties. These local agencies own and operate independent collection systems which are connected to King County's regional system for treatment and disposal.
Sewer maps for individual properties in the city of Seattle may be accessed through the Seattle Department of Planning and Development. An online search tool is available for these maps.
Septic systems treat wastewater when homes and buildings are not connected to public sewer systems. The Public Health Wastewater Program retains as-built plans of septic systems in Seattle and King County.
The historical records below are available at the King County Archives:
Historical water and sewer maps
Please contact the Archives for information about the following records:
Road Services Division historical utilities maps and plans, 1914 -
The King County Road Services Division's Map and Records Center maintains maps and other supporting documentation about the establishment, construction and maintenance of county structures and facilities which are, or have been, the responsibility of the division or its functional predecessors. Original hard-copy, full-size maps are held at King County Archives, while the division maintains digital and microfilm copies and an electronic index to the map holdings. Materials transferred to the King County Archives include maps and plans of water systems, sewer (wastewater) systems, and storm sewer systems. The bulk of these maps date from 1940 but some earlier items are present.
Road Engineer sewer system reference maps, 1940-1960
This collection includes paper copies of sewer system maps maintained as a reference collection by King County engineers. They include:
- Bellevue Sewer District, 1941
- Greenwood sewers (proposed), 1947
- Lake City Sewer District (utility LID #17). 1960
- North Beach #1 sewer extension,1940
- Rainer Vista sewers, 1946
- Ridgecrest sewers, 1940-1950
- Roxbury sewers; as-built, 1945
- Skyway sewerage and drainage district #4, 1942-1944
- Southwest Suburban Sewer District, 1951, 1955
- Val Vue Sewers, 1941
- White Center, 1943
Real Property Division utility franchise files and system maps, c.1940-1988
These records document individual utility franchises issued by King County to water companies; water and sewer districts; and local municipal governments. After 1945, numerous franchises to water companies and water and sewer districts reflect post-World War II housing construction.
Franchise file documents vary over time but generally include a letter of application, a legal description of the proposed franchise, and records of the county's response. Additional correspondence may be present. Maps accompany most text records and may be either annotated copies of commercial or plat maps, or original maps created by the applicant.
Boeing Field maps, 1929-1999
This series includes utility maps (air, electrical, fire systems, lights, plumbing); sanitary and storm sewers, storm drains and pump stations; plans of Boeing Company structures located at the airport; maps of fuel tank locations; environmental inventories and maps and plans relating to water pollution control programs.
For more information about the above records, please contact the Archives.
Historical utility district records
Utility taxing districts, such as water and sewer districts, are not a part of King County government. Records generated and maintained by water and sewer districts are held by the districts themselves or at the Puget Sound Regional Archives, a branch of the State Archives in Bellevue. Please contact the Regional Archives (external link) for additional information.
The collections of the King County Archives document how county government relates to utility taxing districts: establishing them, setting their boundaries, and collecting and distributing taxes raised.
Establishment records for utility taxing districts can be found in county legislative files. Supporting documentation (petitions, resolutions and maps relating to annexations, absorption by incorporated areas, and dissolution) can be found in the King County Commissioners' Water District Files (1916-1973) and Sewer District Files (1936-1972). These records are housed by district number at the Puget Sound Regional Archives (external link). Utility taxing district information can also be found in franchise files held at the King County Archives.
Auditor's annual reports, 1885 -1969
The auditor's annual report of the financial status of King County details monies received from all sources, principally taxes, and the disbursement of monies by county agencies. It also summarizes the county's general resources, liabilities and indebtedness. Records of specialized taxing districts (e.g., water or sewer districts) are presented separately. Please contact the King County Archives for further information about these records.
Department of Transportation photograph and moving image files, 1960-2002.
King County photographers documented neighborhoods and street infrastructure in unincorporated King County prior to sewer or water line construction. Photographs can be found by keyword, road or street name, sewer or water district name or number, intersection, and sometimes homeowner name. Reference maps showing sewer connections and locations of photographs are often present in these files. Please contact the King County Archives for further information about accessing or searching these photographs.
Utility taxing district reports and studies
Please contact the Archives for information about these records:
Department of Planning and Community Development, Building and Land Development Division (BALD). Water and sewer district plans and studies.
This record series contains engineering plans and studies commissioned by municipalities, water and sewer districts in King County. They were most likely collected and kept as a reference collection by the Road Engineer or by the Building and Land Development (BALD) Division.
There are two components: (1) a numeric section for water districts, arranged by water district number, and (2) an alphabetic section arranged by name of municipality, sewer or water district. Many of these are comprehensive plans generated as part of a combined water-and-sewer study for a given district or municipality.
King County Document Collection
This collection of individual reports and studies includes such items as aquifer protection studies; engineering reports; environmental impact statements; hydraulic analyses; sewerage system plans, amendments and updates; and water system plans, amendments and updates. Please contact the Archives for additional information or to locate a specific report.