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Contact with polluted water can make people sick. Stay out of the water for 48 hours after a sewage and stormwater overflow.

Warning: possible sewage overflows during and following heavy rain.

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 an outfall icon to view the current details of each outfall.


Legend for CSO status map

Health Questions?

Public Health Seattle & King County answers questions about CSOs

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.

Alexander Mockos, CSO Capital Programs Manager

Erika Peterson, Project Manager