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North Henderson


North Henderson project area.

What & Why?

What's happening now?

Construction will begin on the Seward Park site in early 2015. The park remains open, but parking will be affected. View parking map (pdf).

Project benefits

The North Henderson CSO Reduction Project (North Henderson) will reduce the amount of untreated sewage and stormwater that overflows into Lake Washington at two outfalls located offshore of:

  • Seward Park - view map of Basin 44 CSO improvements (pdf)
    The project includes additional piping, outfall replacement, with shoreline work and landscape improvements.
  • 57th Ave. S. near Martha Washington Park - view map of Basin 45 CSO improvements (pdf)
    The proposed underground facility for Basin 45 consists of a 16,000 gallon pipe and piping improvements.

The end result

To reduce the frequency of sewage overflows to no more than one per year per outfall, on average, SPU plans to complete two new underground storage facilities in North Henderson in 2017 to store excess combined sewage and stormwater during major rain.


Ask Us

Alan Lord, PE, Project Manager
(206) 233-1565

Please specify the project site with your comments:

  • Seward Park (Basin 44) or
  • 57th Ave. S. right-of-way (Basin 45)

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