Henderson/M.L. King CSO Project

Completed fall 2005

Complete! A clean-water project in the Rainier Beach area of South Seattle

The three-and-a-half-year $77 million project will reduce sewer overflows in your neighborhood and Lake Washington.

The project is one of King County's largest combined sewer overflow control projects. Besides helping protect the water quality of Lake Washington, it provides many needed improvements to the Rainier Beach sewer system, much of which is more than 50 years old.

Before this project, 30 million to 60 million gallons of combined waste and stormwater overflowed to Lake Washington every year from King County combined sewer overlfows (CSOs). With the project complete, CSOs will be dramatically reduced, and our beaches will be cleaner and safer.

 
Construction in Rainier Beach occurred along South Henderson Street , 42nd Avenue South and South Norfolk Street between January 2002 and August 2005. The project included six tunnels.

More photos and description of the completed project:

• How the new CSO project helps protect Lake Washington and Rainier Beach
• Inside the combined sewer overflow storage tunnel 
• What is a CSO? 
• Project Newsletter, October 2005, (PDF, 414 KB)

News about the Project

• News Release, Oct. 26, 2005 -- King County celebrates final major clean-water project for ending overflows into Lake Washington
• Media Advisory, Oct. 25, 2005 -- King County to celebrate startup of new facilities to control overflows of untreated stormwater, sewage
• News Release, Oct. 17, 2003 -- Major King County sewer tunnel to reach daylight on south Beacon Hill
• News Release, Aug. 15, 2003 -- Tunnel rescue training Saturday at Rainier Beach sewer project
• News Release, May 9, 2003 -- Major King County sewer tunneling to begin under south Beacon Hill
• News Release, Aug. 20, 2002 -- Major sewer construction project in Rainier Beach to begin in September