Santa Ana, CA Environmental Rules: Flood Elevation Requirements (2026)

Chapter 7's floodplain regulations tie every elevation requirement to the base flood elevation defined at § 7-5: the water-surface elevation shown on the Flood Insurance Rate Map (FIRM) for zones AE, AH, A1-30, VE, and V1-V30 corresponding to a flood with a one percent or greater chance of occurring in any given year, the flood insurance industry's 100-year flood. Section 7-17(c)(1) sets the construction standard built on that definition: new construction or substantial improvement of a residential structure in an AE, AH, or A1-30 zone must have its lowest floor, including any basement, elevated to or above the BFE.

In an AO zone without a numbered BFE, the lowest floor must instead sit above the highest adjacent grade by at least the depth number printed on the FIRM, or by two feet if no depth number is given. In an unnumbered A zone with no BFE on the FIRM, the elevation is determined under § 7-14(c) and the lowest floor must still reach or exceed that determined elevation. Santa Ana's code, as excerpted here, does not add a local freeboard margin above the BFE for residential construction, the standard is to or above base flood elevation, not a fixed number of feet higher.

Once built, § 7-17(c)(1) requires the lowest-floor elevation to be certified by a registered civil engineer or licensed land surveyor and verified by the city building inspector, with that certification filed with the floodplain administrator. Nonresidential structures instead may floodproof below that same elevation under § 7-17(c)(2), with an engineer's or architect's certification that the structure is watertight and can resist hydrostatic and hydrodynamic loads.