East Ballard Ship Canal

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 29 million gallons of stormwater mixed with some sewage during heavy rains. When the storm passes, flows will be sent to the King County 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

This project will keep more than 75 million gallons of polluted water out of the Lake Washington Ship Canal, Salmon Bay, and Lake Union on average each year. The project will limit CSOs to no more than one per outfall per year on average, in compliance with state and federal laws.