Garden Grove, CA Environmental Rules: Flood Elevation Requirements (2026)

040 establishes the Flood Hazard Overlay Zone (FH) based on the FEMA Flood Insurance Study and Flood Insurance Rate Maps dated February 18, 2004, on file at 11222 Acacia Parkway. No structure or land in the mapped special flood hazard area may be constructed, extended, converted or altered without a development permit issued by the Floodplain Administrator, a role assigned to the City Manager or designee. For residential construction, the code sets the lowest floor, including any basement, at or above the base flood elevation in Zone A and in all other flood zones; it does not mandate extra freeboard as a hard number, but the code notes the state recommends elevating at least two feet above the base flood elevation.

Nonresidential structures may instead be floodproofed below that level so long as walls are substantially impermeable to water and can resist hydrostatic and hydrodynamic loads, certified by a registered engineer or architect. Upon completion, a registered engineer or surveyor must certify the lowest floor elevation, verified by the Community Building Inspector, and that certification goes to the Floodplain Administrator. Development in the floodway is barred outright unless an engineer certifies zero increase in base flood elevation from the encroachment. Violations, including any construction skirting these requirements, are classified as a misdemeanor, and appeals from a Floodplain Administrator decision go to the Planning Commission.