Snohomish County, WA Landscaping Rules: Weed Ordinances (2026)

Unlike many cities, unincorporated Snohomish County does not cap lawn height by ordinance. Weed regulation instead flows from state law: RCW 17.10.140 requires every owner to eradicate Class A noxious weeds and control listed Class B and C weeds within and from their property. RCW 17.10.020 creates a noxious weed control board in each county; the Snohomish County Noxious Weed Control Board publishes the local weed list and, when owners fail to comply, may control the weeds and charge the cost back to the owner. Ordinary overgrown grass alone is generally not a code violation unless it harbors listed noxious weeds or creates a nuisance.