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South Henderson Basin

52nd Ave. S. Combined Sewage Overflow (CSO) Reduction Project

Project map52nd Ave S. and Mapes Creek project map.

SPU is installing a new combined sewer line from Rainier Ave. S., up 52nd Ave. S. (the Mapes Creek Walkway) and along S. Henderson St. to the King County pump station. The new combined sewer line will reduce overflows of combined sewage into Lake Washington during heavy rain events.

It is being constructed in conjunction with the Lower Mapes Creek Restoration Project, which will move flows from Mapes Creek out of a storm drain pipe, into its own dedicated pipe and restore approximately 400 feet of creek channel within Beer Sheva Park. Learn more about the Lower Mapes Creek Restoration Project.

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Project Benefits

  • Protect public health by reducing overflows of raw sewage into Lake Washington.
  • Provide public art to the Rainier Beach community.
  • Improve landscaping within the community.

Project Impacts

  • The S. Henderson St. sidewalk between Rainier Ave. S and Seward Park Ave S. is now fully open to pedestrian traffic.
  • The Mapes Walkway remains closed until mid-August as the artist finishes the public artwork.

Project Schedule

Construction started at the beginning of 2014 and is scheduled to be complete in late September 2014. See the Lower Mapes Creek Restoration Project site for information about the schedule in Beer Sheva Park. Thank you to everyone in the community for your patience and cooperation during construction!

We are also working on a combined sewer overflow reduction project in the North Henderson basin. Please visit the North Henderson Basin website for additional details.


Contact Alan Lord, Project Manager by email or at (206) 233-1565

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