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National Compliance Initiative: Keeping Raw Sewage and Contaminated Stormwater Out of Our Nation's Waters

Boom captures litter and other debris carried by stormwater.
Boom captures litter and other debris carried by stormwater.


Raw sewage overflows and inadequately controlled stormwater discharges from municipal sewer systems introduce a variety of harmful pollutants, including disease causing organisms, metals and nutrients that threaten our communities' water quality and can contribute to disease outbreaks, beach and shellfish bed closings, flooding, stream scouring, fishing advisories and basement backups of sewage.

EPA, in conjunction with state co-plaintiffs, is taking enforcement action at municipal sewer systems with Clean Water Act violations to reduce pollution and volume of stormwater runoff and to reduce unlawful discharges of raw sewage that degrade water quality in communities.


The EPA has almost completed this NCI, obtaining significant improvement in compliance and major reductions in water pollution. Work in FY 2019 will be focused on completing ongoing enforcement cases and monitoring compliance with existing enforcement settlements. In collaboration with authorized state programs, work in these areas will continue as part of core program in FY 2020, especially with a focus on addressing impaired waters.


EPA and authorized states will continue to address combined sewer overflows, sanitary sewer overflows and municipal separate storm sewer system violations and monitor the progress of these long-term agreements, where appropriate adapting them to include green infrastructure practices and new pollution control technology. Green infrastructure helps reduce the water quality impacts of heavy rains and snow melts and is cost-effective and sustainable. Examples include: green roofs, rain gardens, permeable pavements, and revitalization of vacant lots. 


Progress on Keeping Raw Sewage and Contaminated Stormwater Out of Our Waters

The following maps and charts show EPA's progress in targeting the largest municipalities to reduce stormwater runoff and unlawful discharges of raw sewage. Although not graphically displayed, since FY 2010 EPA has also made substantial progress in addressing 192 (75%) of the 253 largest (Phase 1) MS4s.

Map of the status of combined sewer overflow systems (CSO) serving a population of 50,000 or more people

List of consent decrees of combined sewer overflow systems (CSO) with links to the consent decree and data on the status of the decree.

Map of the status of sanitary sewer systems in municipalities with wastewater flow greater than 10 million gallons per day