Flood Zones 101

B, C and X - These areas have been identified in the community FIS as areas of moderate or minimal hazard from the principal source flood in the area. However, buildings in these zones could be flooded by severe, concentrated rainfall coupled with inadequate local drainage systems. Local storm water drainage systems are not normally considered in the communities FIS. The failure of a local drainage system creates areas of high flood risk within these rate zones. Flood insurance is available in participating communities. (Zone “X” is used on new and revised maps in place of Zones B and C.)

D - Unstudied areas where flood hazards are undetermined but flooding is possible. Flood insurance is available in participating communities.

V - SFHA’s along coasts subject to inundation by the 100-year flood with the additional hazards associated with storm waves. Because detailed hydraulic analyses have not been performed, no base flood elevations or depths are shown.

VE & V1-V30 - SFHA’s along coasts subject to inundation by the 100-year flood with the additional hazards due to velocity (wave action). Base flood elevations derived from detailed hydraulic analyses are shown within these zones. (Zone VE is used on new and revised maps in place of zones V1-V30.)

A - SFHA’s subject to inundation by the 100-year flood. Because detailed hydraulic analyses have not been performed, no base flood elevations or depths are shown.

AE & A1-A30 - SFHA’s subject to inundation by the 100-year flood determined in a FIS by detailed methods. Base flood elevations are shown within these zones. (Zone AE is used on new and revised maps in place of zones A1-A30.)

AH - SFHA’s subject to inundation by 100-year shallow flooding (usually areas of ponding) where average depths are between one and three feet. Base flood elevations derived from detailed hydraulic analyses are shown within these zones.

AO - SFHA’s subject to inundation by 100-year shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses are shown within these zones.

A99 - SFHA’s subject to inundation by the 100-year flood, which will be protected by a federal flood protection system when construction has reached specified statutory progress toward completion. No base flood elevations or depths are shown.

Acronyms 

SFHA               Special Flood Hazard Area                 

NSFHA             No Special Flood Hazard Area

FIS                   Flood Insurance Study                        

FIRM                Flood Insurance Rate Map

FEMA               Federal Emergency Management Agency

NFIP                 National Flood Insurance Program

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