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Combined Sewer Overflow

Understanding How to
Protect Our Water

Clean waterways are a priority in Mishawaka. The Wastewater Division is currently implementing many projects to improve our waterways and reduce combined sewer overflows. These efforts include expanding and modernizing our wastewater treatment plant and improving the sewage collection system.

What is a Combined Sewer Overflow?

Combined Sewer Overflows (CSOs) occur when the capacity of the sewer system and treatment plant is exceeded, due to rainfall or snowmelt. When this occurs, the excess mixture of stormwater and sanitary sewage is discharged to the river through combined sewer overflows. (see “Why Sewers Overflow“). The greatest impacts of discharges from CSOs are associated with bacteria in the untreated sewage and the stormwater runoff. Bacteria levels in the river can rise for several days following a CSO discharge. Notification signs have been posted at CSO outfall locations and access points along the river (see “Mishawaka CSO Locations“).

CSO Public Notifications

Mishawaka Utilities is committed to keeping our community’s waterways clean and informing the public of any areas of concern. Federal law (40 CFR 122.38 (c)) requires CSO communities that discharge into tributaries of the Great Lakes to provide public notifications when CSOs are discharging. Initial notification of a CSO event must be communicated within four hours of an overflow beginning, and a supplemental notice must be issued within seven days of the event that gives estimated CSO volume along with overflow start and stop times. A notification summarizing the past year’s CSO activity will be published annually on the City of Mishawaka’s website by May 1 of each calendar year.

To receive notifications about CSO events in Mishawaka, follow the Mishawaka CSO Alerts account (@CSOAlerts) on Twitter. You can also visit the Mishawaka CSO Alerts feed on Twitter directly.

How can I help?

  • Disconnect downspouts and sump pumps from the sewage system.
  • Clean up after your pets.
  • Dispose of household chemicals and used oil properly – not down the drain or a storm sewer.
  • Reduce water use and keep pollution out of the storm drains.
  • Invite us to make a presentation to your civic association or neighborhood group. 

These simple steps can make a world of difference in Keeping Mishawaka Beautiful.