Seattle Public Utilities

Queen Anne Ship Canal Water Quality

NQAShipCanal

The north Queen Anne 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 King County West Point Wastewater Treatment Plant in Magnolia.

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

  • Building a new microtunnel under the Ship Canal to convey polluted stormwater and sewage to the storage tunnel
  • Building a drop shaft to direct flows down into the microtunnel
  • Installing new pipes to convey polluted stormwater and sewage to the drop shaft

What’s happening now?

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

Project goals and benefits

This project will keep over 62 million gallons of polluted water out of the Lake Washington Ship Canal, Salmon Bay, and Lake Union 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.