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Combined Sewer Overflows
Mid-Atlantic Combined Sewer Overflows Quick Finder |
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National Information
Related Mid-Atlantic Information
Combined sewer overflows (CSO) are typically found in older cities. These systems were designed to collect rainwater runoff, domestic sewage, and industrial wastewater all in the same pipe. Most of the time, combined sewer systems transport all of their wastewater to a sewage treatment plant. However, during periods of heavy rainfall or melting snow the volume of wastewater going into the pipes can exceed the capacity and excess wastewater empties directly into nearby streams, rivers, or other water bodies. The mid-Atlantic area of the U.S. contains high concentrations of these systems.
The major challenge in the mid-Atlantic region is that many communities have an antiquated infrastructure that was designed and built prior to modern sanitary engineering practices. Sewage was discharged directly to storm sewers that flowed to receiving streams. The human health effects of untreated sewage discharges (PDF) (26 pp, 175K, About PDF) are an increased incidence of gastrointestinal illness, primarily from contact recreation, such as swimming at beaches.
Many communities in the mid-Atlantic area have received funding assistance to help address their CSO problems. Some of the funding has been provided directly by EPA and other funding has been made available through the Clean Water State Revolving Fund (CWSRF) program.
An illustration of the three types of systems that are used for sewage and stormwater disposal. Larger version of graphic.
CSO Communities (database) in the Mid-Atlantic
