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

Flagstaff City Code Chapter 12-01 defines the Regulatory Flood Elevation (RFE) as one foot above the base flood elevation (BFE) established by FEMA's Flood Insurance Study and Flood Insurance Rate Maps for Coconino County, or as set by the Director of the Arizona Department of Water Resources for watercourses without a mapped BFE. That one-foot cushion is the City's freeboard standard. Under Section 12-01-001-0006.1(A)(3)(a), every new residential structure and every substantially improved or substantially damaged residential structure in Zones AE and AH must have its lowest floor, including any basement, and attached machinery and equipment elevated at or above the RFE; floodproofing is not an allowed substitute for elevation on new residential construction, though nonresidential buildings may floodproof instead under separate standards.

In Zone AO, where no BFE is mapped, the lowest floor must sit at least one foot above the highest adjacent grade, or two feet if the FIRM lists no depth number. A registered professional engineer, surveyor or architect must certify the as-built lowest floor elevation on the FEMA elevation certificate and file it with the Floodplain Administrator, a duty assigned to the Stormwater Section Director or Stormwater Project Manager. A floodplain use permit from that office is required before construction begins in a special flood hazard area, and an attached garage built below the RFE must be designed with openings that let floodwaters enter and exit automatically.

The Floodplain Board, which is the City Council sitting in that capacity, hears appeals of the Administrator's elevation determinations and grants the rare variance, which cannot be issued if it would raise flood levels in the floodway.