Fullerton, CA Environmental Rules: Flood Zones (2026)

Per FMC 14.01.015, the Building Official permits substantial new development within AO, A, and AE zones only when appropriate given flood damage probability, and reviews permits in AE zones to ensure development does not adversely affect flood carrying capacity. Residential construction standards require: in AE zones, the lowest floor (including basement) elevated at least 1 foot above the base flood elevation (BFE); in AO zones, elevated at least 1 foot above the depth number on the FIRM, or at least 3 feet above highest adjacent grade if no depth is specified; in A zones, elevated to or above BFE. An 'AO zone' is defined as shallow flooding 1-3 feet deep during a 100-year storm where flood depth times velocity is less than 15. If any portion of a property falls within an AO zone, the entire property is treated as AO. Applicants submitting hydrologic or hydraulic analyses that change BFEs, hazard boundaries, or floodway designations must submit data to FEMA within six months. Fullerton flood risk is influenced by Fullerton Creek, Coyote Creek, and Carbon Canyon Creek, with Brea, Fullerton, and Carbon Canyon Dams reducing downstream flood risk. Floodplain administration is handled by the Public Works/Engineering Division ((714) 738-6845). California Water Code §§9100, 9620, and 9650 govern state-level floodplain management cooperation with FEMA and require local compliance with NFIP minimums.