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

Section 15.40.210(A) requires new residential construction or substantial improvement to have its lowest floor, including any basement, elevated to or above the base flood elevation in an A zone or any other zone, and in an AO zone, elevated above the highest adjacent grade to the depth number shown on the Flood Insurance Rate Map, or at least two feet above the highest adjacent grade if the FIRM specifies no depth number. The state of California recommends going further, two additional feet above the base flood elevation, but the chapter's floor is the base flood elevation itself.

Once construction is complete, a registered professional engineer or surveyor must certify the lowest floor elevation, and the city building inspector must verify the structure was properly elevated, with both records filed with the floodplain administrator under § 15.40.210(A). Subsection B lets nonresidential construction substitute floodproofing for elevation, requiring a watertight structure with walls substantially impermeable to water, structural components able to resist hydrostatic and hydrodynamic loads, and a matching certification by a registered engineer or architect. Subsection C requires any enclosed area below the lowest floor used only for parking, access or storage to include at least two openings totaling at least one square inch of net area per square foot of enclosed area, with the lowest opening no higher than one foot above grade, so floodwater can enter and exit automatically.

Manufactured homes follow the separate elevation standards in § 15.40.240 instead. The floodplain administrator, the city engineer under § 15.40.150, keeps every certification required by this section on file for public inspection per § 15.40.160(D).