Casa Grande, AZ Environmental Rules: Flood Elevation Requirements (2026)

Under Casa Grande Municipal Code § 15.40.460, the City defines 'regulatory flood elevation' (RFE) as an elevation one foot above the base flood elevation (BFE) shown on the FEMA flood insurance rate map, giving Casa Grande a one-foot freeboard above the federal minimum. Section 15.40.750 applies that freeboard to residential construction: in Zone AO, the lowest floor (including basement) must be built to or above the regulatory flood elevation, or at least two feet above the highest adjacent grade where no FIRM depth number is specified; in a Zone A where no base flood elevation has been determined, the lowest floor must reach the regulatory flood elevation or an elevation set using criteria from FEMA or the Arizona Department of Water Resources; and in Zone AE, the lowest floor must simply be at or above the regulatory flood elevation.

Before occupancy, a registered professional engineer or surveyor must certify the lowest floor elevation on an elevation certificate delivered to the floodplain administrator. Enclosed areas below the lowest floor that can flood, such as crawl spaces used only for parking, access, or storage, must have at least two flood vents on different walls providing one square inch of net opening per square foot of enclosed area, with vent bottoms no higher than one foot above grade, engineered to automatically equalize hydrostatic pressure. Nonresidential structures may instead be dry-floodproofed to or above the regulatory flood elevation under Section 15.40.740, built watertight and structurally able to resist hydrostatic and hydrodynamic loads, subject to engineer or architect certification.