Flagstaff, AZ Environmental Rules: Flood Zones (2026)

Flagstaff's floodplain regulations, adopted under Chapter 12-01, apply to all areas within the City's corporate limits, including special flood hazard areas and administrative floodplains identified on FEMA's Flood Insurance Rate Maps for Coconino County, and the rules extend automatically to any land the City later annexes. No structure or development may be constructed, located, extended, converted or altered in a special flood hazard area without a floodplain use permit issued by the Floodplain Administrator; the application must show lot elevations, proposed lowest-floor elevations and drainage facilities, and for subdivisions over fifty lots or five acres it must include base flood elevation data.

Inside the regulatory floodway, the strictest zone, the code bars encroachments outright: fill, new construction, footprint-expanding additions, storage of materials or equipment, manufactured homes, recreational vehicles and any other development are prohibited unless a FEMA map revision removes the area from the floodway. A substantial improvement can proceed there only if a hydrologic and hydraulic 'no-rise' certificate, prepared under standard engineering practice, shows it will not raise flood levels during the base flood. Waste disposal facilities, wastewater treatment ponds and new private sewage systems are banned in the floodway outright, and storage of buoyant, flammable, explosive or toxic materials is barred there and throughout the special flood hazard area.

Where no floodway has been separately mapped, Zone A is treated in its entirety as a regulatory floodway. The Floodplain Board, the City Council sitting in that role, must approve the rare variance from these rules, and the Floodplain Administrator must act on a complete permit application within thirty days.