Find out if a combined sewer overflow (CSO) is overflowing
Check before going swimming, wading, fishing, or boating near a CSO warning sign
Contact with polluted water can make people sick. Stay out of the water for 48 hours after a sewage and stormwater overflow.
We are testing out a new map to display CSO status. We will be continuing to update the functionality of the map over time. Click on the symbol for a CSO outfall icon to view the current details of each CSO outfall.
About this information
This map gives the most current information on recent overflows. During heavy rains, pipes that carry sewage and stormwater together can overflow through relief points called combined sewer overflows (CSOs). This information is provided to allow people to make informed decisions about using our local waters. It is the most current information available. It has not yet been reviewed for accuracy. People can review confirmed data in monthly and annual reports that King County and Seattle submit to the Washington State Department of Ecology.