Goodyear, AZ Environmental Rules: Flood Elevation Requirements (2026)

The one-foot freeboard standard comes from the definitions article of Chapter 16: § 16-2-1 defines REGULATORY FLOOD ELEVATION as an elevation one foot above the base flood elevation for watercourses where a BFE has been set, with the Director of Water Resources setting the criteria for any watercourse without a determined BFE. That definition feeds directly into the construction standards of § 16-5-1(C). New residential construction and substantial improvements in Zones AE, AH and A1-30 must have their lowest floor, including any basement, elevated to or above the regulatory, one-foot-freeboard elevation rather than the bare base flood elevation.

In an A Zone where FEMA has not pinned down a BFE, builders elevate to the regulatory base flood elevation or follow criteria the Director of Water Resources sets instead. In a Zone AO, where flood depths are shown as shallow ponding rather than a mapped elevation, the standard shifts to at least two feet above the highest adjacent grade when the map carries no depth number. Once the structure is finished, § 16-5-1(C)(1) requires the lowest floor elevation to be certified by a registered professional engineer or surveyor and verified by the City's building inspector, with that certification filed with the Floodplain Administrator.

Nonresidential buildings get an alternative compliance path: instead of elevating, they can be flood-proofed watertight below the same regulatory elevation, with a professional engineer or architect certifying the flood-proofing design under § 16-5-1(C)(2). Attached garages built with the floor slab below the regulatory flood elevation must be designed to let floodwater automatically enter and exit rather than trap it against the structure.