180th St SE - Phase I

Description - Completed

Snohomish County’s six-year Transportation Improvement Plan (TIP) identifies projects to improve conditions for pedestrians and motorists, including along 180th St SE near Mill Creek.

The 180th St. SE - Phase I project expanded the three-lane road to five lanes from SR 527 to 23rd Ave SE. As part of this project, the merger of Thompson Creek and Silver Creek was relocated from the north side of 180th St SE to the south side, with each creek flowing beneath 180th St. SE through separate fish-passable culverts.  

The project also added sidewalks, bike lanes, curbs, planter strips, and gutters within the project boundaries. Crews rebuilt the traffic signals at 180th St SE and Brook Blvd and created new stormwater detention and treatment facilities.


Construction began in spring 2020 with a temporary month-long pause in work due to a statewide shutdown for COVID during March and April of 2020. The project resumed and was completed by fall 2021 as previously planned. 


The project was awarded a $4 million grant from the Washington State Transportation Improvement Board for construction funding and was the beneficiary of a $3 million loan from the Public Works Trust Fund.

Environmental Review

An environmental review and Checklist was completed in compliance with the State Environmental Policy Act (SEPA) on March 2, 2018 for Phase I of the proposed 180th St. SE road improvement project.

Snohomish County Public Works determined that this project does not have a probable, significant adverse impact on the environment and has issued a Determination of Non-significance (DNS).

Public Comment & Appeal Period

The SEPA comment period regarding this project ended on March 26, 2018.


This project was awarded the American Public Works Association (APWA) 2023 Project of the Year Award for the Transportation $5-25 Million category. View the award submission.

Public Meetings

Snohomish County Public Works held a public meeting on June 27, 2017 to discuss four projects in this area. The projects were the 35th Ave SE - Phase II, 43rd Ave SE/Sunset Rd, 180th St SE Phase I and II, and 196th St SE/Grannis Rd. Staff was available to answer questions, review proposed improvements, and gather feedback on potential designs. The project was also featured during the fall 2019 meeting featuring the 43rd Ave SE/Sunset Rd Improvement Project.


Other Projects in the Area