Combined Sewer Overflow - CSO

What is CSO?

Why Our Sewers Overflow When It Rains

More than 100 years ago, South Bend, Mishawaka, Elkhart and many other cities built storm sewers to carry rainwater and melting snow away from homes, businesses and  streets. In those horse-and-buggy days, these cities didn't have sewage treatment or even indoor plumbing.

When indoor plumbing came later, homeowners and business owners hooked their sewage lines to the existing storm sewers, combining storm water and raw sewage into one pipe. The pipes emptied directly into the river, until the 1950's when sewage treatment plants were built.

This was common practice in many U.S. cities, especially in the Northeast and Midwest.

During dry weather, a "combined" sewer system works much like a separated sewer -- carrying all sewage to the treatment plant for treatment.

However, when it rains or snow melts, the sewers can be overloaded with incoming stormwater. When this happens, the sewers are designed to flow over internal dams in the underground pipes and into nearby streams and rivers. If they didn't have this release valve, raw sewage would back up into people's basements and streets.

Millions of gallons of untreated sewage and rainwater enter the river each year. State and federal regulations require cities to develop longterm plans to reduce these overflows.

Between 2010 and 2013, the City of South Bend will spend $70 million to reach the mid-point of its CSO long-term control plan. Read more about the plan in the June 2010 River Report*.

Mayor Stephen J. Luecke has summarized the City's effort to provide clean water in a letter to business leaders*.

The South Bend Common Council has received three presentations from Public Works Director Gary Gilot about the City's progress in addressing combined sewer overflows and its plans for the future.

  1. Accomplishments in Phase 1A (2005-2009) *
  2. Plans for Phase 1B (2010-2013) *
  3. Moving forward*

Additional information presented to the Council regarding proposed sewer-rate increases:

You also may read about the beginning of the City's CSO long-term control plan in the June 2005 River Report.

View the CSO Notification Page

Visit the City of South Bend Facebook page for project updates.