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FEMA Flood Zones
FEMA FLOOD ZONES & EXPLANATIONS

 The table below explains the flood zones that can be viewed on a community's flood insurance rate map (FIRM):


Annual Probability of Flooding of 1% or greater

A

Subject to 100-year flood. Base flood elevation undetermined.

AE or A1-A30

Both AE and A1-A30 represent areas subject to 100-year flood with base flood elevation determined.

AH

Subject to 100-year shallow flooding (usually areas of poundings) with average depth of 1-3 feet. Base flood elevation determined.

 

AO

Subject to 100-year shallow flooding (usually sheet flow on sloping terrain) with average depth of 1-3 feet. Base flood elevation undetermined.

 

A99

Subject to 100-year flood, with federal flood protection system (levee/dam) under construction. Base flood elevation undetermined.

 

V

Subject to 100-year flood and additional velocity hazard (wave action). Base flood elevation undetermined.

 

VE or V1-V30

Both VE and V1-V30 represent areas subject to 100-year flood and additional velocity hazard (wave action). Base flood elevation determined.

 

In SFHA

Areas in a "Special Flood Hazard Area" (or 100-year flood plain). Subject to 1% annual chance flooding. No distinctions have been made between the different flood hazard zones that may be included within the SFHA.

 

Flood Prone Area

An area designated as a "Flood Prone Area" on a map prepared by USGS and the Federal Insurance Administration. This area has been delineated based on available information on past floods. This is an area inundated by 1% annual chance flooding for which no base flood elevations have been determined.

 

Annual Probability of Flooding of 0.2% to 1%

 

X500

Areas between the limits of the 100-year and 500-year flood; or certain areas subject to 100-year flood with average depths less than 1 foot or where the contributing drainage area is less than 1 square mile; or areas protected by levees from the 100-year flood.  These zones are shown on the FIRM as shaded "X" zones.

 

Annual Probability of Flooding of Less than 0.2%

 

X

Areas outside the 500-year flood plain with less than 0.2% annual probability of flooding.

 

Annual Probability of Flooding of Less than 1%

 

No SFHA

Areas outside a "Special Flood Hazard Area" (or 100-year flood plain). Can include areas inundated by 0.2% annual chance flooding; areas inundated by 1% annual chance flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; areas protected by levees from 1% annual chance flooding; or areas outside the 1% and 0.2% annual chance floodplains.

 

Undetermined

 

D

Unstudied areas. Flood hazards are undetermined.