Seattle Public Utilities

3rd Avenue West Water Main Replacement


The City of Seattle will construct a new water pipe between Fremont and Queen Anne.

What & Why

The 3rd Avenue W Water Main Replacement Project will construct a new 24-inch feeder main in a utility tunnel (referred to as a “utilidor”) under the Lake Washington Ship Canal between Fremont and Queen Anne. The new feeder main (feeders provide drinking water service and benefits to a broader geographic area) will replace an existing main that served Seattle for almost 100 years and had reached the end of its service life.


In July 2011, the existing water main was taken out of service due to a leak. In order to minimize construction impacts to the community, SPU agreed to wait until King County’s Fremont Siphon project was completed in 2017 before starting construction. The Fremont Siphon project installed a new siphon to transport sewage and stormwater under the Lake Washington Ship Canal.

Project goals and benefits

The new 24-inch main will provide improved drinking water service and benefits to a broader geographic area. The feeder main improves service levels in Fremont, as far north as Ballard, west to Interbay and Magnolia, and neighborhoods in the immediate vicinity including the base of Queen Anne hill on the east, north, and west side.

Additionally, the new water main will improve pressure, fire flow (the flow rate of water from hydrants used by firefighters), and service reliability in the event other drinking water infrastructure is disrupted.


Fernando Platin, project manager
(206) 615-0991

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Learn more about King County’s Fremont Siphon project