During dry weather, combined sewers that serve the older part of Fort Wayne carry sanitary sewage from homes and businesses to the Water Pollution Control Plant without incident. However, when it rains, combined sewer overflows (CSOs) happen due to the volume of water entering the pipe system thus pushing it past its capacity. As a result, river quality may be impaired by the untreated wastewater that discharges from combined sewers into the City's three rivers at overflow locations.

The main pollutants in CSOs are untreated human and industrial wastes, toxic materials like oil and pesticides, and floating debris that may wash into the sewer system. These pollutants can affect your health of anyone recreating in CSO-polluted water. The pollutants in CSOs can impair use of the rivers and cause a variety of bacteria-related illness. CSO pollutants are not just a human health concern, they also damage the environment of fish, shellfish, and other aquatic life.