35th Ave SE Corridor, Phase I (180th St SE to 152nd St SE (Seattle Hill Rd)


Snohomish County is making improvements to the 35th Ave SE corridor between 180th St SE and 152nd St SE (Seattle Hill Road). The corridor is an important north-south route for Snohomish County residents in a rapidly developing area of the county. The project includes adding bike lanes, center turn lanes, planter strips, sidewalks, and stormwater detention and treatment facilities. The improvements will improve traffic flow and help ease congestion during busy morning and afternoon commutes. The addition of continuous center turn lanes will reduce delays caused by turning vehicles. The plan also includes dedicated bike lanes and sidewalks on both sides of the road.

35th Ave SE Corridor – Phase 2
between SR 524 to 180th St SE will be constructed after 35th Ave SE Phase 1 is completed.


Construction began June 4, 2018 and is expected to be completed by the summer of 2019.

2011-2018: Design, survey, environmental review, right-of-way acquisition
The process of developing road projects takes several years. Many factors must be considered, including: location of homes; public right-of-way; stormwater runoff, drainage and water quality; wetlands and buffers; hilly terrain; sight distance; soils; traffic volumes; accident history; vehicle and pedestrian access; location of utilities; and information that residents provide about the area. 

  • 2011: Completed surveying the topography of the project area
  • 2013: Completed environmental review 
  • 2015: Right of way purchase completed
  • 2018: Construction begins in spring


Environmental Review

An environmental review was completed in compliance with the SEPA. An environmental checklist was prepared on July 26, 2013.

A Determination of Non-significance (DNS) and Notice of Land Disturbing Activity (LDA) Permit were issued on July 26, 2013. They are also available for viewing at Snohomish County Public Works during normal business hours:

  • Cover Letter
  • DNS and Land Disturbing Activity Permit
  • Environmental Checklist
  • SEPA / LDA Notice: August 4, 2013
  • SEPA / LDA Notice Sign Posted: August 2, 2013


Public Comment & Appeal Period

The DNS and LDA 21-day comment and appeal period ended on August 26, 2013. Stephanie Cotton, 425-262-2481, is the contact for the environmental process.


As part of the widening project, Snohomish County completed the purchase of right of way adjacent to the road from property owners along 35th Ave SE. For more information on the right-of-way acquisition process, contact Kurt Lytle at 425-388-6457. The process is also included in the Before we Build Pamphlet.

Public Meetings

Snohomish County Public Works held an open house to discuss the 35th Ave SE - Phase I project on April 25, 2018 at Mill Creek Elementary. Information about the project was available along with project experts to answer questions from the public.

Snohomish County Public Works held a public meeting on February 23, 2017 to discuss three projects in this area. The projects were Seattle Hill Rd, 35th Ave SE, and 156th St SE. Staff was available to answer questions about the construction on Seattle Hill Rd, review proposed road improvements to the section of 35th Ave SE, and gather feedback on potential designs for the 156th St SE project.


Other documents

Other Projects in the Area