Martha Lake North Inlet, Stormwater Facility Improvement


Snohomish County Surface Water Management (SWM), a division of the Department of Conservation and Natural Resources, is planning an underground stormwater treatment system on Lakeview Road that will benefit water quality for nearby natural habitats and people swimming, playing in, or using Martha Lake. 

Snohomish County considered up to six potential locations north of Martha Lake that would benefit water quality the most and narrowed them down to this location near Lakeview Rd and 4th Ave W, based on the amount of stormwater runoff it would treat, estimated cost, and ease of access for future maintenance. At this site, runoff from a 174-acre area between Interstate-5 and Martha Lake will be treated using an underground stormwater filtration system before reaching  the lake.  


The project is currently under Preliminary Design through 2024. Construction is currently planned for 2026, but the schedule is subject to change.

Traffic Impact

Lakeview Rd would require a temporary road closure and detour near the intersection with 4th Ave W, but local access will be maintained during that time. This website will be updated with more information when the start date for the road closure has been identified.


Snohomish County SWM has submitted an application to the Department of Ecology for grant funding for this project.