Shallow flooding zone with sheet flow, 1-3 feet deep
Where AO sits
A / AE Inside the 1%-a-year floodplain: about a 26% chance of flooding over a 30-year mortgage. AE has a mapped base flood elevation; plain A does not.
Floodway The channel and the land beside it that has to be kept clear enough to carry the flood. Building here is tightly limited.
X shaded The 0.2% (500-year) floodplain, plus some levee-protected and very shallow flood areas.
X Outside both lines. No federal requirement to insure, which is not the same as no risk.
What Is Zone AO?
Zone AO designates areas with a 1% annual chance of shallow flooding in the form of sheet flow on sloping terrain. Unlike ponding (Zone AH), water in AO zones moves across the surface.
Flood depths are typically 1-3 feet. Instead of BFEs, FEMA specifies flood depths for Zone AO areas.
Flood Insurance Requirements
Flood insurance is required if you have a mortgage from a federally regulated or insured lender, or a federally backed loan such as FHA, VA, Fannie Mae or Freddie Mac. Zone AO is a Special Flood Hazard Area.