CSO - Combined Sewer Overflows

During storm events, wet weather flow from the City of Chicago's combined sewer system is diverted into the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC)'s Tunnel and Reservoir Plan (TARP) system. When the capacity of TARP is reached, combined sewage may discharge into local waterways via combined sewer overflows (CSO) to alleviate the burden on the sewer system.


For notification of CSO and floodwater discharge events, please go to MWRDGC's website at http://geohub.mwrd.org/pages/cso.


Members of the public can sign up to receive e-mail and/or text notifications of CSO and floodwater discharge events by accessing the MWRDGC's website at http://apps.mwrd.org/CSORegistration/Register.aspx.


If a discharge from a CSO during dry weather is observed, please call 311.

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