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CSO Public Notifications Map

The purpose of the Northeast Ohio Regional Sewer District Combined Sewer Overflow Public Notification System is to alert the public of possible Combined Sewer Overflows or water quality impacts from combined sewer overflows.


Understanding the map

The points on this map are
combined sewer overflow outfall
locations. Under normal conditions,
these points are gray to indicate
no alerts are reported.


Overview: Combined sewers and water quality

Combined sewers carry sewage and stormwater in the same pipe, a design dating back to the end of the 19th century upon which many cities like Cleveland still rely on today. During dry weather, the combined sewer system has the capacity to transport all the flows entering the system for treatment. However, when flow in the sewer increases as a result of heavy rainfall and/or snowmelt and system capacity is reached, the sewer system allows stormwater and sewage to discharge to a waterbody by means of combined sewer outfalls (CSOs) to prevent and protect neighborhoods and treatment facilities from flooding.

When a CSO is overflowing, public health officials advise against recreational contact with water bodies for at least two days (48 hours) after a rain event. Viewing this website before potential water contact is highly recommended.

About the map and monitoring

The Northeast Ohio Regional Sewer District maintains an extensive flow monitoring network. Monitors record data throughout the combined sewer system at various overflow structures and outfalls. Currently, the Northeast Ohio Regional Sewer District operates and maintains monitoring equipment at, or near, 21 of the 122 CSOs throughout the service area. The 21 monitored sites are marked with stars . Unmonitored sites are marked with circles .

This public notification system is based on analysis of monitoring data which is used to report combined sewer overflows during a wet weather event at these 21 CSO sites. This public notification system also provides overflow notification during dry weather at all 122 CSOs throughout the service area.

Information on this site is updated routinely. If an outfall reports that no overflow is occurring, but it is raining, there is still a potential that an overflow is occurring.


The Northeast Ohio Regional Sewer District Combined Sewer Overflow Public Notification Map is a pilot program. The Northeast Ohio Regional Sewer District is constantly updating and improving the notification system in order to deliver the best information possible to the public.

Flow monitoring is a difficult task that requires constant maintenance. It should be assumed some monitors may occasionally report inaccurate information and sometimes no information at all. Please let us know how this system is working for you! Questions or comments regarding information should be directed to Customer Service.

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