Maple Road and Ash Way Intersection and Drainage Improvements

August 2018 Update

The final steel pile was placed last month marking a milestone for the project. Below are photos showing the construction progress. View larger photos in PDF format
Ash Wa yMaple Rd Progress


Snohomish County and the city of Lynnwood are working together to help ease flooding in the vicinity of the Maple Rd and Ash Way/Interurban Trail intersection. Flooding events originating from Swamp Creek force multiple intersection closures per year at this site. 

The project will reconstruct approximately 700 feet of Maple Rd and 600 feet of Ash Way, along with the Interurban Trail, using structural slabs on top of steel piles. The new intersection will be raised roughly five feet from its current elevation and a minimum of six inches above the existing 25-year flood elevation of Swamp Creek. New fish-passable culverts will be installed on Maple Rd and Ash Way.


Snohomish County and the city of Lynnwood held an open house for this project on March 15, 2018. Construction will begin during the spring of 2018, taking approximately two construction seasons to complete.

Traffic Impact / Road Closure

The intersection is closed from April 23 to November 2018 for construction. The Interurban Trail is also closed between Beech Rd (behind the Target store) and Alder Way. With consideration of public input, the detour for the Interurban Trail has been removed from the project plan. Access to all businesses will be available during the project.



The design and construction is fully funded by Snohomish County Public Works Surface Water Management Urban Growth Area revenues and the city of Lynnwood.

Environmental Review - Public Notice

An environmental review of the Maple Rd and Ash Way Improvements was completed in compliance with the State Environmental Policy Act (SEPA). A SEPA Environmental Checklist was issued for this project on July 15, 2016. The drainage system was modified from the original design to reduce impacts to the adjacent wetlands and streams. A SEPA Addendum was issued on March 17, 2017. All SEPA related documents are available by viewing the links below.

Open House (March 2018)

Snohomish County and the city of Lynnwood held an Open House on March 15, 2018 at Lynnwood City Hall in the City Council Chambers. County and city Public Works staff members were on hand to give information about the project and answer questions.



For More Information