Georgetown Wet Weather Treatment Station

Georgetown Wet Weather Treatment Station in Seattle, WA

Georgetown Wet Weather Treatment Station

An Envision® Platinum Stormwater Pollution Prevention Plan

King County’s Protecting Our Waters Program aims at preventing pollution caused by excess stormwater in the sewer system during heavy rains. Combined sewer overflows are relief points in sewer systems that prevent sewage backups into homes and businesses, but they also pollute local water bodies. In 2012, the King County Council adopted an amendment to the Long Term Combined Sewer Overflow Control Plan to address the County’s remaining CSOs. The LTCP calls for control of the Brandon Street CSO and the South Michigan Street CSO into the Duwamish River to no more than one untreated event per year on a long-term average. These CSOs will be controlled by the new Georgetown Wet Weather Treatment Station. 

Since 2013, we are part of a consultant team led by Jacobs to provide comprehensive engineering and consulting services for siting, environmental compliance, property acquisition, design permitting, and services during construction and commissioning. 

In 2017, King County qualified for a $129 million loan from the Environmental Protection Agency’s Water Infrastructure Finance and Innovation Act program. The County was one of only 12 communities nationwide selected for the first round of funding aimed at helping spark investment in critical water infrastructure projects across the country. With construction completed in time for 2022-23 winter rainy season, the Georgetown WWTS will be able to treat up to 70 million gallons of combined stormwater runoff and wastewater per day, which would otherwise have discharged directly into the river without treatment during storm events.

In 2018, the $275 million Georgetown WWTS received the Envision® Platinum designation for sustainable infrastructure, awarded by the Institute for Sustainable Infrastructure. To reach Platinum status, a project has to demonstrate that it delivers a range of environmental, social, and economic benefits to the host and affected communities. The Georgetown WWTS was the third Envision-recognized project in Washington state and the first to receive the Platinum award.

Georgetown Wet Weather Treatment Station in Seattle, WA
King County

Seattle, WA
United States

Up to 70 million gallons of combined rain and wastewater treated a day
Envision® Platinum


Gold Award (2024)
Best in State, Original or Innovative Applications of New or Existing Techniques
American Council of Engineering Companies of Washington
Municipal Water Protection Award (2022)
Pacific Northwest Clean Water Association