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EPA report documents CSO, SSO progress and problems

WASHINGTON—In a report requested by Congress, the U.S. Environmental Protection Agency (EPA) in August summarized the extent and the hazards of combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) in the United States . The EPA estimates in its Report to Congress: Impacts and control of CSOs and SSOs (available online at www.epa.gov/npdes/csossoreport2004)that in 31 states and the District of Columbia , 772 combined sewer systems with more than 9,000 CSO outfalls annually discharge about 850 billion gallons of untreated wastewater and stormwater. From the 19,000 municipal sanitary sewer systems in the United States , the EPA estimates that between 23,000 and 75,000 SSOs occur each year, discharging 3 billion to 10 billion gallons of untreated wastewater.


This is significantly less than 1 percent of the nearly 11 trillion gallons of treated wastewater that municipal sanitary sewer systems discharge annually, according to EPA estimates.

Nevertheless, the EPA said that 3,500to 5,500 gastro-intestinal illnesses each year are caused by CSOs and SSOs that impact coastal and Great Lakes beaches. Since 1998, the EPA has concluded 15 CSO enforcement cases and 25 SSO enforcement cases, collecting more than $14 million in civil penalties and $11 billion in injunctive relief to protect public health and the environment.

The EPA report includes descriptions and case studies on 23 technologies for reducing the impacts of CSOs and SSOs. Additionally, the EPA suggests the following four strategies:

  • provide adequate funding for maintenance and improvement of the nation’s wastewater infrastructure;
  • integrate wastewater programs and activities at the watershed level;
  • improve monitoring and reporting programs to provide better data for decision makers; and
  • support stronger partnerships among federal and state agencies, municipalities, industry, non-governmental organizations, and citizens.