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Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

Magnolia Wet Weather Storage Facility at Smith Cove

Learn more about facility operation

King County crews investigating sewer pipe damage in Magnolia

King County staff and contractors are investigating damage to a County sewer pipeline located 150 feet below the surface of the West Galer Street right-of-way. This pipeline serves the Magnolia Wet Weather Facility. The facility is designed to store wastewater and stormwater during large storms to prevent combined sewer overflows (CSOs) into Puget Sound.

On Friday, Dec. 2, County contractors will start installing sensors and cable in the right of way of W. Galer St. between Northwest. 28th Street and Magnolia Way West. The sensors will help evaluate potential soil loss in the area along the pipeline. The contractor will drill 1-inch diameter holes in the right of way and extend cable along the southern curb. The equipment will be installed by Saturday, Dec. 3. The holes will be filled after the cable is no longer needed.

For more information:

For more information, contact Doug Marsano at or 206-477-5549.

Magnolia Wet Weather Storage Facility
The Magnolia Wet Weather Storage Facility at Smith Cove began storing excess flows of stormwater and sewage in late 2015. The facility’s 1.5 million-gallon underground storage tank helps keep sewage and stormwater out of Puget Sound during storms.

King County is Protecting our Waters

This project is part of King County’s Protecting our Waters program to prevent pollution caused by excess stormwater in the sewer system on rainy days.

Combined sewer overflows (CSOs) are relief points in older sewer systems that carry sewage and stormwater in the same pipe. When heavy rains fill the pipes, CSOs release sewage and stormwater into rivers, lakes, or Puget Sound.

King County and the City of Seattle are working together to control CSOs and keep sewage and stormwater out of local waterways.


Doug Marsano at or 206-477-5549

Facility details

Project vicinity map
South Magnolia basin and project location.