NEW YORK, NY, Aug. 1, 2011 -- A new report from U.S. EPA answers commonly asked questions about combined sewer overflows with specific examples from New York, New Jersey, and Puerto Rico.
Many of the sewer systems in New York State and New Jersey and some in Puerto Rico are combined systems that overflow during heavy rains. Controlling sewage that gets washed into local waterways when it rains is critical to protecting water quality.
The report, Keeping Raw Sewage and Contaminated Stormwater Out of the Public's Water, contains important information about stormwater, combined sewer overflows, and actions that can be taken to protect waterways from CSOs. For example:
• Many communities have separate sewer systems for wastewater collection -- an independent sewer system that carries sewage from buildings and another for rainwater, also referred to as stormwater. The stormwater is sent directly to lakes, rivers and streams, while domestic sewage is transported to wastewater treatment plants, where it is treated to remove pathogens and other contaminants.
• Combined sewer systems, on the other hand, are designed to transport sewage, industrial wastewater and rainwater runoff in the same pipes to wastewater treatment plants. They are remnants of the country's early infrastructure and are typically found in older cities. Combined sewer systems serve about 40 million people in roughly 772 communities nationwide. Most communities with combined sewer systems are located in the Northeast and Great Lakes regions, and the Pacific Northwest.
• Most of the time, combined sewer systems are able to transport all of the wastewater to a treatment plant, where it is treated and then discharged into a water body. During periods of heavy rainfall or snowmelt, however, the volume of wastewater traveling through a combined sewer system can exceed the capacity of the sewer system or treatment plant. For this reason, combined sewer systems are designed to overflow occasionally and discharge excess wastewater directly to nearby streams, rivers, lakes or other water bodies. These overflows, called combined sewer overflows, contain not only stormwater but also pollutants such as untreated human and industrial waste, toxic materials and debris.
• Stormwater contains pollutants, including oil, grease and toxic substances, picked up as rain washes across roads or fields. These pathogens, solids and toxic pollutants may be discharged directly to local waters when it rains, resulting in a discharge that exceeds water quality standards. They pose risks to human health, threaten aquatic habitats and life, and impair the use and enjoyment of the nation's waterways.
• Under the federal Clean Water Act, combined sewer discharges are prohibited without a permit. In December 2000, Congress amended the Clean Water Act by adding a section that requires each permit issued for a discharge from a municipal combined sewer system to "conform" to a national combined sewer overflow policy. The policy is a comprehensive national strategy to ensure that local governments, permitting agencies, entities that establish water quality standards and the public engage in a comprehensive and coordinated planning effort to achieve combined sewer overflow controls that ultimately meet health and environmental standards.
To read or download a copy of the report, visit http://www.epa.gov/region2/water/
For more information about requirements of the Clean Water Act and how EPA protects the nation's water, visit http://water.epa.gov/.