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Why does King County need to do this project?

This project is part of a larger Combined Sewer Overflow (CSO) Control Plan Amendment that will reduce combined sewer overflows into local water bodies and protect public health and the environment. In this plan, there are 14 current or approved projects left to complete to reduce overflows that occur in the regional wastewater system. Duwamish projects, including the Georgetown Wet Weather Treatment Station, were prioritized based on what King County heard from the community.

This facility greatly reduces untreated wastewater and stormwater from entering the Duwamish.

Facility design

Visit the public involvement page to learn more about the Design Advisory Group (DAG).

Birdseye view of treatment stationBirdseye view of treatment station from corner of 4th Avenue South and South Michigan Street 

Working together for a sustainable project site

The King County Wastewater Treatment Division (WTD) included community members in the Georgetown Wet Weather Treatment Station project's decision making. Through the project Design Advisory Group, Georgetown community members and businesses advised the project team on the station design. Additionally, over 100 neighborhood community members shared their thoughts on the project. The station design includes the following elements based in part on input from the community to ensure the station promotes environmental and social sustainability:

New trees

  • Filter stormwater
  • Improve air quality
  • Add tree canopy—an important community health indicator

A green roof

  • Cleans and absorbs stormwater
  • Limits the station’s heat contribution to the atmosphere
  • Creates educational opportunities for community members

Cisterns and rain gardens

  • Collect stormwater for irrigation
  • Improve the station’s appearance
  • Highlight simple ways we all can take to control pollution

Explaining how the station works

People will be able to tell when and how the treatment station is at work in the following ways:

  • Special lights along the building will light up when the station is working.
  • Passersby will be able to see what’s going on inside through the fencing and the building itself.
  • Colored pipes will show water’s path through the station.
  • Interpretive signs posted in areas open to the public.
  • One of the station’s operation buildings will have space available for Wastewater Treatment Division educational and training events with local schools and other educational partners.

blue_pipesPipes will be colored to show water’s path through the building.

Connecting to the river

The treatment station’s cleaned water will flow through underground pipes to enter the Duwamish River underneath the SR-509 Bridge. The area around the Duwamish entry point will include:

  • Native plants and logs installed to stabilize the river bank
  • Improved wildlife habitat.

Location of plant outfall. The area around the Duwamish entry point will include native plants, logs installed to stabilize river bank, and improved wildlife habitat 

New public art

King County WTD spends 1% of the cost of design and construction of an eligible project’s above ground structures on public art installations.

For the Georgetown project, the Combined Sewer Overflow (CSO) Master Plan artists want the treatment station art to serve as “a monument to rain.” Their art will work to remind us of the hidden infrastructure all around us, and highlight how weather interacts with it to benefit us.

Stay tuned for more information about an Evening of Art to learn more about public art and art opportunities at the treatment station.

Art_600Public art will be included at the treatment station. This artwork is located at WTD’s Brightwater Treatment Plant (Brightwater Center).


Contact us

Contact Kristine Cramer at:


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The county is also investing in projects around the Georgetown neighborhood to improve water qualityThe county is also investing in projects around the Georgetown neighborhood to improve water quality. The County supported the design and installation of a rain garden and two cisterns at Carleton Avenue Grocery.

Cisterns will store more than 35,000 gallons of rain water from the station's roof each year. The stored water will be used to water the station's plants and trees, which will improve air quality. 

The view from the First Avenue South Bridge to South Michigan Street when the station is working on a rainy night.

Conceptual rendering showing the future treatment station as vehicles and passersby approach from the north on 4th Avenue South.

The station will have a meeting room available in one of its operations buildings for educational and training events.

Conceptual rendering showing southeast corner of the treatment station, intersection of 4th Avenue South and South Michigan Street.