Seattle Public Utilities

Ballard Ship Canal Water Quality


The existing 24th Avenue NW pedestrian pier will be replaced.


Like older parts of Seattle, Ballard, Fremont, North Queen Anne, and Wallingford are served by a combined sewer system. In dry weather conditions, all sewage flows to King County’s treatment plant in Magnolia. During wet weather conditions, flows can exceed the pipes’ capacity and send a mixture of stormwater and sewage into the nearest body of water. These combined sewer overflows or “CSOs” contain contaminants that could make people sick and harm fish, wildlife, and the environment.