Renton, WA Environmental Rules: Flood Zones (2026)

Renton participates in the National Flood Insurance Program and enforces floodplain management regulations under Renton Municipal Code 4-3-050 for all Special Flood Hazard Areas shown on the FEMA Flood Insurance Rate Maps. The primary flood zones in Renton are along the Cedar River through downtown and the former Black River corridor in the Tukwila and Renton lowlands, mapped largely as Zone AE with base flood elevations. Lake Washington shoreline properties near the Cedar River mouth are also affected. New construction, substantial improvements, and additions within the Special Flood Hazard Area must have the lowest floor (including basement) elevated to at least 1 foot above Base Flood Elevation (BFE) as a city freeboard requirement, and non-residential structures may use floodproofing in limited cases. Fill placement in the floodplain requires a Floodplain Development Permit and typically compensatory storage. Critical facilities and manufactured homes face additional rules. Flood insurance is mandatory for federally backed mortgages in the Special Flood Hazard Area. Contact CED at (425) 430-7200 to request a Letter of Map Amendment or confirm your flood zone.