Lynnwood, WA Environmental Rules: Flood Elevation Requirements (2026)

Chapter 16.46 LMC implements the National Flood Insurance Program inside Lynnwood, Snohomish County, based on the Flood Insurance Study for Snohomish County and the accompanying FEMA flood insurance rate maps adopted by reference at LMC 16.46.030(B). Before any construction or development, including fill, begins within a mapped area of special flood hazard, LMC 16.46.040(A)(1) requires a development permit from the city's public works director, supported by plans showing the proposed lowest-floor elevation relative to mean sea level and, for nonresidential floodproofing, an engineer's or architect's certification.

The one-foot freeboard standard sits in the specific standards at LMC 16.46.050(B)(1)(a): new construction and substantial improvement of a residential structure must have its lowest floor, including any basement, elevated one foot or more above base flood elevation, which exceeds the bare federal minimum of matching base flood elevation. Nonresidential buildings can meet the same one-foot standard by floodproofing instead of elevating, with the structure watertight below that level and certified by a registered engineer or architect. Critical facilities, such as schools, hospitals, and emergency response buildings, must clear three feet above base flood elevation if they cannot avoid the floodplain entirely. Manufactured homes and recreational vehicles have their own elevation and anchoring rules under LMC 16.46.050(B)(4) and (B)(5). Variances from the one-foot standard go to a three-member appeal board the mayor appoints, and Lynnwood requires written notice to the applicant that a below-grade variance can raise flood insurance premiums by as much as $25 per $100 of coverage.