Seattle Overflow Action Plan
Shape Our Water CSO Illustration by Natalie Dupille.
Reducing pollution in our waters
The Seattle Overflow Action Plan describes the path Seattle Public Utilities’ (SPU) is taking to reduce combined sewer overflows (CSOs), when stormwater (rain) and wastewater (sewage) overflow into waterways during heavy storms. Learn more about CSOs in Seattle.
This plan updates the 2015 Plan to Protect Seattle’s Waterways, builds on SPU’s CSO achievements, and meets requirements under the Modified Consent Decree with the U.S. Environmental Protection Agency and the Washington State Department of Ecology. It will assess current and future needs, identify priorities, and guide investments through 2037. Preliminary planning will take place through 2026 followed by project design and implementation from 2026-2037.
The Seattle Overflow Action Plan will help SPU:
- Protect public health and the environment by reducing overflows and backups, especially in neighborhoods with historical underinvestment, while improving water quality in our creeks, lakes, and other waterbodies.
- Build resilient, cost-effective solutions that account for future system challenges, meet federal and state requirements, and comply with regulations over time.
- Align with community priorities and invest in multi-benefit solutions.
- Partner with King County where our systems are connected.
See the range of potential strategies in SPU’s Shape Our Water solution toolbox.
Community involvement
Seattle Overflow Action Plan engagement team will partner with community-based organizations, City partners, and community members to provide inclusive and equitable community engagement, centering on underrepresented communities.