Combined Sewer Overflow Program Progress

Communities with combined sewer overflows (CSOs) have made significant progress towards meeting the CSO Control Policy and Clean Water Act requirements. Since the early 1990s, the number of CSOs that occur each year has decreased, along with the volume of these discharges. The number of CSO outfalls has also decreased, as has the number of communities with CSOs.

EPA estimates that as CSO communities implement their long-term control plans, nationwide progress over time will show significant reductions of key parameters and improved water quality.