Clean Water Act

"No one has the right to use America’s rivers and America’s waterways, that belong to all the people, as a sewer. The banks of a river may belong to one man or one industry or one state, but the waters which flow between the banks should belong to all the people."
- President Lyndon B. Johnson

In 1972, Congress passed the Clean Water Act, the primary federal law governing water pollution, which is administered by the Environmental Protection Agency (EPA).

Seattle is on EPA’s list of nearly 800 cities in the U.S. that operate a combined sewer system, pipelines that carry both wastewater and stormwater.

The Clean Water Act requires that CSOs happen no more than once per outfall per year. To achieve and maintain that goal the utility is developing a comprehensive Long-term Control Plan (LTCP)  to define all CSO reduction projects throughout Seattle.

In some cases, the EPA can issue an Administrative Order or Consent Decree to include additional requirements to comply with state and federal guidelines concerning CSO control.

In 2009, the Environmental Protection Agency (EPA) issued a compliance order to direct the City of Seattle and King County to step up efforts to reduce CSOs.

The EPA has delegated authority to the Washington State Department of Ecology to enforce clean water standards. Seattle’s drainage and wastewater system is permitted under the National Pollutant Discharge Elimination System (NPDES), which allows CSOs during rainy weather. In accordance with both state and federal law and its NPDES permit, the City is required to reduce CSOs through both shorter-term best management practices (BMPs), proper operations and maintenance programs, and longer-term more capital-intensive projects.

2016-2021 NPDES Combined Sewer System Permit Fact Sheet (pdf)

2016-2021 NPDES Combined Sewer System Permit (pdf)