Fremont Ship Canal Water Quality

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.

The Ship Canal Water Quality Project includes the following activities in Fremont:

  • Building the new storage tunnel
  • Installing new pipes to convey polluted stormwater and sewage to the tunnel
  • Building a drop shaft to collect flows entering the tunnel near the intersection of 2nd Avenue NW, Leary Way NW and NW 36th Street
  • Building a new microtunnel under the Ship Canal to convey polluted stormwater and sewage from Queen Anne to the new storage tunnel
  • Providing odor control equipment to minimize odor

What’s happening now?

Elements of the Ship Canal Water Quality Project in Fremont 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.