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Construction of the Brightwater facility began in 2005 and the plant began operation in September 2011 to serve portions of King and Snohomish counties.

rsz_15093140244_63a5baa5f3_zConstruction of Brightwater wetlands

View more photos on our Flickr site  .

Contact us

24 hour emergency and odor reporting:   206-263-9500
Administration:   206-263-9465

22505 State Route 9 S.E.
Woodinville, WA 98072-6010

Directions and map


  • 1999: Regional Wastewater Services Plan is adopted and King County begins a process to site the Brightwater treatment facilities.
  • Summer 2000: King County forms an interdisciplinary team to work on the siting process. Ninety-five areas are initially analyzed for engineering and environmental constraints.
  • May 2001: County council selects six candidate sites and eight marine outfall zones for further consideration.
  • June 2001: King County Executive Ron Sims finds that two of the systems offer significant opportunities that could benefit surrounding communities and further regional goals. Based on his recommendation, the county council selects Unocal and Route 9 systems to continue the environmental review process.
  • 2005: Construction of the treatment plant, conveyance system, and marine outfall begins.
  • 2011: Treatment plant construction completed.
  • September 2011: The Brightwater facility began treating wastewater. 
  • 2012: Conveyance construction completed.

Regional system history

In 1958 voters approved the creation of a regional wastewater treatment system to clean the wastewater being generated from the developing cities. Metro was formed as the organization to build and manage this system and was later merged with King County. More regional wastewater system history.