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Local sewer agencies

King County provides wholesale wastewater treatment services to 18 cities, 15 local sewer utilities, and the Muckleshoot Indian Tribe in King, Snohomish, and Pierce counties.

These local agencies own and operate independent collection systems, which include pipelines and pump stations to collect and carry wastewater flows in their service area to King County's regional system for treatment and disposal. The local agencies have 30-year agreements with King County for this service. King County owns and operates the regional treatment plants, pipelines, pump stations, and other related facilities.

The county does not bill individual property owners for sewer service. Instead, it charges the local agencies an amount that is based on the county's monthly rate and the number of customers the agency serves. In turn, the local agencies bill their customers to recover the county charge plus the amount needed to operate and maintain their collection systems.

Local sewer agencies served by WTD

Alderwood Water & Wastewater District
City of Algona, Public Works
City of Auburn, Utilities
City of Bellevue, Utility Services
City of Black Diamond, Public Works
City of Bothell, Public Works
City of Brier, Public Works
City of Carnation, Public Works
Cedar River Water & Sewer District 
Coal Creek Utility District 
Cross Valley Water District 
Highlands Sewer District 
City of Issaquah, Public Works
City of Kent, Public Works
City of Kirkland, Public Works
City of Lake Forest Park, Public Works
Lakehaven Water & Sewer District 
City of Mercer Island, Sanitary Sewer Utility
Muckleshoot Indian Tribe, Public Works
Northeast Sammamish Sewer & Water District 
Northshore Utility District 
Olympic View Water and Sewer District 
City of Pacific, Public Utilities
City of Redmond, Public Works
City of Renton, Public Works
Sammamish Plateau Water & Sewer District 
City of Seattle, Public Utilities
City of Shoreline, Wastewater Utility
Skyway Water and Sewer District 
Soos Creek Water & Sewer District 
City of Tukwila, Public Works 
Valley View Sewer District (formerly Val Vue Sewer District) 
Vashon Sewer District 
Woodinville Water District