Skip to main content
Press Release

Seattle and King County, Wash., Agree to Upgrade Combined Stormwater Systems to Protect Local Waters from Raw Sewage Overflows

For Immediate Release
Office of Public Affairs
City & County Combined Sewer Overflows Expected to Drop by up to 99% by 2030

King County, Wash. and the city of Seattle have agreed to invest in major upgrades to local sewage and combined stormwater collection, piping and treatment under settlements with the Department of Justice and the U.S Environmental Protection Agency (EPA). The state of Washington was a co-plaintiff and partner in these settlements.

The agreements are the result of extensive federal and state government cooperation and pave the way for employing more “green infrastructure” projects like green roofs, permeable pavements and urban runoff gardens, which help reduce demands on local sewer and stormwater systems.

“Today’s settlement will substantially reduce overflows of sewage-contaminated stormwater into the Puget Sound and other area waterways and significantly benefit the environment and health of residents of King County and Seattle,” said Ignacia S. Moreno, Assistant Attorney General for the Justice Department’s Environment and Natural Resources Division. “The agreement provides a long-term planning approach to managing the area’s stormwater that integrates green infrastructure and requires improvements to system-wide sewer operations and maintenance.”

 “EPA is working with cities and counties to find smart, effective solutions to reduce raw sewage and contaminated stormwater,” said Cynthia Giles, assistant administrator for EPA’s Office of Enforcement and Compliance Assurance. “Today’s settlements allow Seattle and King County to use innovative solutions, like green infrastructure, to help dramatically improve local water quality.”
“We’re pleased with the commitments King County and Seattle make in these legal agreements to reduce and control these overflows off Seattle’s shores,” said Maia Bellon, Washington state Director of Ecology.  “The Consent Decrees allow flexibility in selecting and coordinating clean water projects, while setting firm dates to finish the job.”
 Both agreements allow the city and county to use an integrated planning approach, which encourages communities to set their own clean water project priorities and invest in fixing the most pressing problems first. The settlements also require King County and Seattle to develop and implement a joint plan to improve system-wide operations and maintenance, since Seattle conveys the combined sewage it collects to King County’s system for treatment prior to discharge.


Under the terms of the county settlement, King County will implement a long-term plan for controlling sewer overflows. By implementing these measures, King County will reduce its raw sewage discharges by approximately 95 to 99 percent, better protecting Puget Sound, Lake Washington and the Duwamish River from sewage-laced overflows. The improvements and upgrades are expected to cost approximately $860 million. In addition, King County will pay a civil penalty of $400,000.

The agreement allows the county to substitute green infrastructure projects, like green roofs, permeable pavements and urban gardens, which help reduce the demands on local sewer and stormwater systems, at four of its sewer overflow control projects. 

Between 2006 and 2010, King County discharged approximately 900 million gallons of raw sewage to waters of the United States on an annual basis through discharges from its combined sewer system. During this time period, the county also violated the effluent limitations of its discharge permit, including fecal coliform at more than one of its wastewater treatment plants, and allowed wastewater to bypass secondary treatment at one of its wastewater treatment plants in violation of its discharge permit and the Clean Water Act.


Under the settlement with the city of Seattle, the city will develop and implement a long-term plan for better controlling sewer overflows and improve system-wide operations and maintenance. The city will also implement plans to control fats, oils and greases, and reduce debris being discharged by the system. In addition, the settlement provides Seattle with the opportunity to also use an integrated planning approach and to substitute green infrastructure at several of its sewer overflow control projects. By implementing these measures, the city will reduce its raw sewage discharges by approximately 99 percent at an estimated cost of $600 million.  Seattle will also pay a civil penalty of $350,000.

Between 2007 and 2010, Seattle discharged approximately 200 million gallons of raw sewage into area waterways on an annual basis. During this time period, the city also improperly operated and maintained its sanitary sewer system, resulting in unauthorized discharges of raw sewage to public and private properties, including basement backups.
Keeping raw sewage and contaminated stormwater out of the waters of the United States is one of the EPA’s top priorities. Reductions in sewer and stormwater overflows are accomplished by obtaining cities’ commitments to implement timely, affordable solutions to these problems, which may also include the use of Integrated Municipal Stormwater and Wastewater Plans. This approach can also lead to more sustainable and comprehensive solutions, such as green infrastructure, that improve water quality and enhance community vitality.

The settlement, lodged today in the U.S. District Court for the Western District of Washington, is subject to a 30-day public comment period and approval by the federal court.  The consent decree can be viewed on the Justice Department website:

More information about the settlement:

More information about EPA’s national enforcement initiative:

More information about Integrated Municipal Stormwater and Wastewater Plans:

Updated September 15, 2014

Press Release Number: 13-432