West Duwamish Wet Weather Storage Facility
King County’s plans to build a wet weather storage facility to hold stormwater and wastewater that currently overflows into the Duwamish River during large storms.
Project description
King County will build a 1.25-million-gallon underground storage facility near the intersection of SW Michigan St and 2nd Ave SW to hold stormwater and wastewater that currently overflows into the Duwamish River during large storms. The water in the storage facility will then flow to the West Point Treatment Plant for treatment before it is safely released into Puget Sound. This storage facility will reduce overflows and pollution into the Duwamish River. The County will also build supporting infrastructure underneath West Marginal Way SW.
The project has recently reached the 60 per cent design milestone. At 60 per cent design, the project details are determined including equipment, architecture, landscaping, and contractor documents (design drawings and specifications). The project team is now focused on finalizing design details and preparing for construction, which will begin in 2025.
Project update
June 2023
Meet the local artists selected to create artwork connected to the West Duwamish Wet Weather Storage Facility project!
4Culture and the Wastewater Treatment Division commissioned artists Laura C. Wright and Timothy White Eagle to create temporary artwork in the Duwamish Valley that will stimulate curiosity and raise awareness of the largely invisible underground stormwater and wastewater system. Guided by community input, the West Duwamish Wet Weather Storage Facility will improve water quality in the Duwamish Valley. The selected artists will be guided by the CSO Art Master Plan developed by artist team Sans Façon. To learn more about Laura C. Wright and Timothy White Eagle, read 4Culture’s E-News: Two Artists selected for the West Duwamish Art Opportunity - 4Culture.
Subscribe to the project listserv to receive updates as their work progresses.
Read the most recent project newsletter to learn more about this clean water project.
Previous project updates
- Frequently asked questions, August 2023
- Potholing near 1st Ave S Bridge beginning May 25, May 2023
- Spring newsletter, March 2023
- Surveying near 1st Ave S Bridge beginning November 2, October 26, 2022
- Lane closure on 2nd Avenue SW - October 19 and 20, October 17, 2022
- Design is progressing on the West Duwamish Wet Weather Storage Facility, July 2022
- Soil testing near 1st Avenue South Bridge starting week of May 16, May 2022
- New storage tank near SR 509 will reduce sewage and stormwater spills into the Duwamish River during big storms, November 2021
- West Duwamish CSO Control Project Environmental Review; Opportunity for community input in January, Fall 2021
- Soil sampling and groundwater testing near 1st Avenue South Bridge Week of May 7, May 1, 2018
- West Duwamish CSO Control Project Winter 2017 newsletter, November 2017
- Highland Park project update, October 2017
- Soil and groundwater sampling near 1st Avenue South Bridge Week of June 26, June 18, 2017
- Soil and groundwater sampling near 1st Avenue South Bridge May 30 through June 5, May 23, 2017
- West Duwamish CSO Control Project newsletter, July 2016
- South Park & Highland Park Green stormwater infrastructure newsletter, February 2014
- South Park: Well installation in your neighborhood beginning as early as February 6, February 3, 2014
- South Park: Well installation in your neighborhood beginning November 11, November 5, 2013
- Highland Park: Well installation in your neighborhood beginning November 11, November 4, 2013
- King County source control project in our Duwamish, (2MB), July 2013
Consultants, contractors & suppliers: learn about upcoming construction projects including the West Duwamish Wet Weather Storage Facility.