As communities began to develop in the Midwest, many designed sewer systems that not only carried wastewater from homes, commercial business, and industries, but also served as a means to collect and funnel storm water to local treatment plants. These combined sewer overflow (CSO) systems discharged to neighboring surface waters in the event of heavy rain events or snow melts. At a time with less impervious surfaces, these discharges were infrequent and the system worked as designed. However, today larger volumes of combined wastewater and stormwater are discharging into our waterways; having a drastic impact on water quality. The EPA's CSO Control Policy is the guiding framework for communities looking to control their CSOs to meet Clean Water Act goals in an efficient manner.
