Reducing Combined Sewer Overflows
Approximately one third of our City has a Combined Sewer System where stormwater and wastewater are combined. During heavy rains, this system is more likely to overflow into our local waters; this is called a combined sewer overflow or CSO. Use our map to find current or recent overflows.
Since 2008, we have invested almost $1 billion to reduce CSOs. We are reducing pollution in our waters. Learn more about our commitment to CSO reduction:
- Hear more about Our Commitment to Reducing Combined Sewer Overflows
- Find our largest CSO project, the Ship Canal Water Quality Project
- Learn more about SPU’s Plan to Protect Seattle’s Waterways (2015)