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Projects
Find information about current and planned future Mouth of Duwamish Wet Weather Facilities projects.
January 2025
Thank you for learning about Mouth of Duwamish Wet Weather Facilities!
King County started planning for Mouth of Duwamish Wet Weather Facilities a year ago. Since then, we have made good progress and engaged with the community to raise awareness about this important project to protect public health and improve water quality.
We expect to wrap up the planning phase this spring. At that time, we will share our proposal for facilities to control overflows from the Mouth of Duwamish combined sewer overflow (CSO) outfalls within regulatory requirements. King County will then seek approval of our proposed plans from regulatory agencies, including the Washington State Department of Ecology. We will also begin a review under the State Environmental Policy Act (SEPA) to consider environmental impacts.
Read our 2024 year-end project update for more information about our progress last year and what to expect looking forward.
Stay connected!
As we progress through planning, design, and construction, we will continue to provide opportunities for you to ask questions and share thoughts and concerns. For project updates, join our email list using the link in the “stay informed” section of this webpage or by scanning the QR code below.
Can’t make it to one of our virtual or in-person events? Contact Bibiana Ocheke-Ameh at bibiana.ocheke-ameh@kingcounty.gov or 206-477-5604 with questions or to request a briefing for your organization.
Project description
King County is currently evaluating methods to reduce overflows from 5 combined sewer outfalls (shown on the map below) in accordance with Washington State law and the federal consent decree. These methods may include storage, treatment, or conveyance and will result in a variety of future projects.
During the planning phase, the project team will recommend an approach to control CSOs that considers a number of factors including regulatory, cost, environmental, and community priorities. King County’s regulators will review and approve plans before the projects move into design and construction.
We anticipate planning to end in fall 2025, with design and construction of projects associated with the Mouth of Duwamish Wet Weather Facilities to immediately follow.
King County is seeking to understand the feasible options to control pollution from these outfalls and meet regulatory and environmental requirements.
Community outreach
For information about community outreach, visit the Mouth of Duwamish Wet Weather Facilities public engagement webpage.