Palmdale, CA Environmental Rules: Flood Elevation Requirements (2026)

120(C) sets Palmdale's elevation and floodproofing standards for all areas of special flood hazard. In an AO Zone, new residential construction must have the lowest floor, including any basement, elevated to or above the flood depth number shown on the Flood Insurance Rate Map, or at least two feet above the highest adjacent grade if no depth number is specified. In an A or AE Zone, and in every other special flood hazard zone, new residential construction and substantial improvements must have the lowest floor, including basement, elevated to or above the base flood elevation itself, meaning Palmdale imposes no additional freeboard cushion beyond the mapped base flood elevation outside the AO zone's two-foot standard.

Once the structure is complete, a registered professional engineer or surveyor must verify the lowest floor elevation, and the City Building Inspector must confirm the structure was properly elevated, with that certification delivered to the Floodplain Administrator. Nonresidential construction can instead be dry floodproofed watertight below the base flood level, with structural components able to resist hydrostatic and hydrodynamic loads, certified by a registered engineer or architect. All new construction and substantial improvements must also use flood-resistant materials and utility equipment below the base flood elevation, and enclosed areas below the lowest floor used only for parking or storage must have flood vents equal to at least one square inch of opening per square foot of enclosed area, with the bottom of openings no higher than one foot above grade.

140 extends the elevation-certification duty to subdivisions and manufactured home parks larger than 50 lots or five acres, which must identify the base flood elevation and certify final pad elevations for any site filled above it.