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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

Murray CSO control project -- Building a new storage tank to protect Puget Sound

Project Construction

November 16, 2016 -- Underground storage tank now working! Restoration of nearby streets and sidewalks continues

King County’s million-gallon underground storage tank is now working after passing all system tests. As early as next week, County operators will work inside the facility to monitor flows at the Murray Pump Station and operate the underground storage tank as needed.

Roadway restoration is complete on Beach Dr. S.W. The contractor is now restoring sidewalks near the site. Crews are also working in the access road south of Lowman Beach Park to upgrade a small sewer line. This work is expected to be complete by mid-December.

Schedule update
Landscaping and project art will finish up in early 2017, depending on weather (see schedule in attached update for additional information). A fence will remain around the site until all landscaping is complete. The public staircase on site will not be accessible until all project work is complete. Access to Lowman Beach Park will be maintained as it has been throughout construction.

King County and its contractor appreciate your patience as we work to complete the project as quickly as possible. We will provide another update in December with what to expect during activities that will continue in 2017.

For additional information about the schedule and what to expect, see the latest project update (PDF).

Please direct any questions or concerns to the project hotline: 206-205-9186.

Murray Project Hotline: 206-205-9186

Learn more about Final Facility Design
Final Design
, December 2012

Murray basin and project location
Murray basin and project location

Project description

King County is designing an underground storage tank across the street from Seattle’s Lowman Beach Park. The tank will store approximately one million gallons when the Murray Pump Station exceeds maximum capacity.

Why do we need this project?

Protect public health

Like many cities around the country, the older parts of King County's wastewater system uses a single set of pipes to carry untreated sewage and stormwater to a treatment plant. To prevent sewer backups into homes and streets, the system includes safety valves called “combined sewer overflows” that route excess sewage and polluted stormwater flow directly into Puget Sound during storms. Although CSOs reduce potential exposure to untreated sewage, they pose significant public health concerns.

Clean up Puget Sound

The Murray CSO control facility will reduce CSOs into Puget Sound. State regulations require no more than one untreated discharge per year. The Murray Pump Station averages five untreated CSO events per year, discharging 5 million gallons into Puget Sound off of Lowman Beach Park.

Project schedule

Construction schedule

How has the community shaped facility design?

Since October 2011 Lowman Beach Park neighbors and park users have worked with local designers, environmentalists and community advocates to help the King County project team design a facility that fits with the community. These discussions produced “common themes” for the design that reflect the community’s values for a safe, reliable facility. The common themes are:

  • Minimize the “industrial facility” feel
  • Encourage views of Puget Sound
  • Discourage through traffic on Beach Drive
  • Enhance continuous space between Lowman Beach park and the facility site

Southbound vehicles on Beach Drive SW can use the access road south of the park to turn around
Southbound vehicles on Beach Drive SW can use the access road south of the park to turn around.

Have a question or concern? Please use the project feedback form.

Project updates

Find out if a CSO is occurring in Murray

Related information

  • To learn more about the Project Planning Phase (CSO control alternatives selection process in the Murray basin, 2007 to 2010), please see the Facility Plan.
  • Protecting Our Waters (Combined Sewer Overflow Control Program), King County 

For more information

This project is funded in part by:

Department of Ecology, State of Washington