What Are CSOs?

Combined Sewer Overflows

When it rains, the sewer system can't handle the large volume of sewage and storm water. This is called a combined sewer system because both sewage and storm water flow into one pipe. Instead of allowing water to back up into people's basements during a rainstorm, the combined sewer system allows the polluted water to be discharged directly into the Rouge River. This discharge into the river is known as a combined sewer overflow or CSO.

At the beginning of the Rouge Project in 1992, combined sewers serviced about 20 percent of the Rouge River Watershed, with 168 CSO discharge locations. This mixture of sewage and storm water contained pollutants that resulted in a public health threat to those that came into contact with the water. At present, only a fraction of the uncontrolled CSO discharges still exist. Each of those remaining discharges is under a program to be controlled by 2005.

Please address all comments and suggestions about the contents of this Web page to DOEHelp@co.wayne.mi.us.

The Rouge River National Wet Weather Demonstration Project is funded, in part, by the United States Environmental Protection Agency (EPA) Grants #XP995743-01, -02, -03, -04, -05, -06, -07, -08, -09, and C-264000-01.