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Last year, King County engaged businesses, residents, and community partners in South Park to prepare for construction. In 2026, we will begin building an underground storage tank near the intersection of Southwest Michigan Street and Second Avenue Southwest. The storage tank will hold stormwater and wastewater during large storms, helping keep pollution out of the Duwamish River.
 Facility site prior to construction (October 2025) and facility rendering once construction is completed
Construction coming soon!
Construction at the storage tank site will begin as early as spring 2026. Once construction begins, you can expect:
- Increased noise and vibration from construction vehicles and equipment
- Large trucks and equipment moving in and out of the project area
- Work on West Marginal Way Southwest, Second Avenue Southwest, Southwest Michigan Street, and Highland Park Way Southwest
- Temporary lane closures with traffic control directing vehicles and bicyclists around work areas
- Sidewalk closures with pedestrian detours
- Work taking place on weekdays during permitted daytime work hours
- Advance notice will be provided for any night work, weekend work, or new traffic impacts
- Maintained access for people biking, walking, and rolling near the site and on the Duwamish Trail
Please watch for equipment and signs in the area, travel slowly to stay safe and follow direction from flaggers.
We expect construction to last through mid-2029. We will share regular updates throughout construction to keep you informed. Stay tuned for more!
 West Duwamish Wet Weather Storage project timeline
Thank you for your input!
At the start of this year, we hosted a survey to gather feedback on our efforts to keep you informed during the design phase. We heard from people who live, work, and travel in South Park and Highland Park. We also asked nearby businesses to tell us about their needs during construction. Thank you for staying engaged and helping us to work better together!
Meeting you in the community
In March, we partnered with South Seattle College Georgetown Campus to host a job fair. The job fair promoted careers in clean water and sustainable building. Over 100 community members attended the event.
We also attended community fairs and celebrations in South Park and Georgetown. We shared information about upcoming construction and answered your questions.
 The project team at the Duwamish Valley Celebration in Georgetown.
Partnering for workforce development
We are partnering with Villa Comunitaria to promote workforce opportunities. Villa Comunitaria is a group in South Park that supports community building. Together, we are connecting families and students to internships and job training programs.
Questions?
Interpretation and translation services are available to you at no cost. If you need them, please contact Daniel Arauz at 206-437-6486 or daarauz@kingcounty.gov.
Alternative Formats Available: 206-477-5371 or TTY Relay: 711
Looking inside a wastewater treatment lab
When you flush the toilet or wash your hands in the sink, water travels down the drain to a treatment plant to get cleaned before it can be released back into the environment.
Staff at the South Treatment Plant Lab in Renton test water samples from three of our treatment plants to ensure that the water we return to Puget Sound is clean and safe. They monitor microbes — key organisms that help break down organic waste — as well as nutrient and oxygen levels that can affect our environment and marine life. Join Wastewater Process Analyst Kennedy Tisdel to see the work happening in the lab.
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