NFIP Flood Zone Explanations

NFIP FLOOD ZONE EXPLANATIONS

(December 2023)

 

The National Flood Insurance Program (NFIP) uses a zoning system for assigning an area’s vulnerability to flood losses. A variety of maps are commonly used to show a given community’s or locale’s various zone designations.

 

Example: This flood designation map is merely for illustrative purposes.

 

Here is an explanation of the flood zone designations used by the NFIP and FEMA:

 

NFIP FLOOD ZONES

Zone

Special Flood Hazard Areas - High Risk

Mandatory flood insurance purchase is required.

Floodplain management standards apply.

A

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

AE or A1-A30

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 ponding) with an 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.

AR

Previously accredited flood protection system has been decertified and is in the process of being restored to provide a 100-year or greater level of flood protection.

A99

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

Zone

High Risk – Coastal Areas

Mandatory flood insurance purchase is required.

Floodplain management standards apply.

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.

Zone

Moderate to Low-Risk Areas

B, X (shaded)

Both B and X500 represent areas between the limits of the 100-year and 500-year flood. It also applies to 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.

C, X (unshaded)

C and X represent areas outside the 500-year flood plain with less than 0.2% annual probability of flooding.

Zone

Undetermined Risk Area

D

Unstudied areas. Flood hazards are undetermined.