Seattle Public Utilities

East Ballard Ship Canal Water Quality


The east Ballard site for the Ship Canal Water Quality Project.

What & Why

Seattle Public Utilities (SPU) and King County’s Ship Canal Water Quality Project is a 2.7-mile, 18'10"-diameter tunnel that will capture and temporarily hold more than 15 million gallons of stormwater mixed with some sewage during heavy rains. When the storm passes, flows will be sent to the existing West Point Wastewater Treatment Plant in Magnolia.

In east Ballard, Ship Canal Water Quality Project activities occur near 11th Avenue NW and NW 45th Street. These activities include building:

  • New pipes to convey polluted stormwater and sewage to the drop shaft
  • A drop shaft to direct stormwater flows into the tunnel
  • Below ground vaults for electrical, mechanical, and odor control equipment

What’s happening now?

Elements of the Ship Canal Water Quality Project in east Ballard are currently in the design phase. Construction is expected in 2019.

Project goals and benefits

Once complete, the Ship Canal Water Quality project will prevent over 60 million gallons of raw sewage and polluted stormwater from flowing into Lake Union, the Ship Canal, and Salmon Bay each year.