Seattle map of real-time CSO status | King County Wastewater Treatment Division

King County CSOs -- Seattle overview

Below is a map showing the 38 CSOs that are operated by King County. Thirty two of the locations have real-time information available because they are part of the computerized system that controls the wastewater system. The other six are monitored, but the information is not monitored in real time. Data from these locations is manually entered into the system by staff.

Annual reporting of CSO discharges (number of times and the volume of the discharge) is available in King County's Annual CSO reporting to the Department of Ecology.

King County Combined Sewer Overflow Locations

About this map

The CSO status information on this page is updated every 10 minutes.

Move your cursor over the map and click to view detail Seattle CSO maps by region:

Data displayed on this map has not been reviewed by King County. King County reviews all CSO data on a regular basis and determines if an overflow truly occurred at a location.

Maintenance or equipment malfunction may show a false CSO discharge. Official data is available in King County's Annual CSO reporting to the Department of Ecology.

This map does not show information for the 90 City of Seattle CSOs.

The purpose of this Web page is to give the public the opportunity to make decisions about the use of waterways during heavy rains. CSOs usually discharge in the winter between October and May. During the CSO discharge and for 48 hours following the discharge, water users near the CSO locations are at risk from exposure to bacteria in the water.

This is a pilot program that we are continually trying to improve and make useful. Please let us know how this is working for you and any comments or suggestions you may have.