ABOUT THE RIVER > THE COMBINED SEWER SYSTEM

The Washington, D.C. sewers add another level of contamination to the Anacostia via the combined sewer system that underlies the oldest part of the city. Approximately one-third of the city, including the Capitol Building and most federal government buildings, are on this system, built at the end of the 19th century.

In dry weather, the combined sewer system transports both sanitary sewage (waste water from toilets, sinks, washing machines, etc.) and anything running into a street-side storm drain to the Blue Plains Wastewater Treatment facility.

However, when there is rain or a snowmelt of over a half inch (approximately 80 times per year), the system overflows and discharges untreated waste - both polluted rainwater and raw sewage - into the Anacostia. More than three billion gallons of overflow goes directly into the river in an average year. Bacteria levels from the discharge are often thousands of times over safe levels, making it unhealthy to swim, fish and in some cases, even boat on the Anacostia.

In December 2004, two lawsuits filed in federal court against DC Water and Sewer Authority were settled. The negotiated settlement requires WASA to build large underground tunnels to store sewage and rainwater when the combined sewer system is full to capacity. When the combined system can again handle more flow, the material from the storage tunnels will be pumped to the Blue Plains wastewater plant for treatment. Along with other controls, the tunnels are expected to cut sewage overflows by 97% to the Anacostia River, 93% to the Potomac River and 90% to Rock Creek in an average year.

The settlement provides for completion of the first tunnel in about 13 years, with the remaining tunnels completed within 20 years. This schedule is based on the premise that the federal government will not be contributing to the cost of the construction. Current financing plans involve water bill rate increases for DC citizens and businesses averaging approximately 7.7% per year for each of the next 20 years. If federal funding becomes available, the schedule could be tightened and the cost to the district reduced.
For more about the combined sewer system, visit
DC Water and Sewer Authority's website.