Flooding can happen anywhere, but certain areas are especially prone to serious flooding.
To help communities understand their risk, flood maps (Flood Insurance Rate Maps, FIRMs) have been created to show the locations of high-risk, moderate-to-low risk, and undetermined-risk areas. Here are the definitions for each:
High-risk areas (Special Flood Hazard Area or SFHA)
High-risk areas have at least a 1% annual chance of flooding, which equates to a 26% chance of flooding over the life of a 30-year mortgage. All homeowners in these areas with mortgages from federally regulated or insured lenders are required to buy flood insurance. They are shown on the flood maps as zones labeled with the letters A or V.
Moderate-to-low risk areas (Non-Special Flood Hazard Area or NSFHA)
In moderate-to-low risk areas, the risk of being flooded is reduced, but not completely removed. These areas are outside the 1% annual flood-risk floodplain areas, so flood insurance isn’t required, but it is recommended for all property owners and renters. They are shown on flood maps as zones labeled with the letters B, C or X (or a shaded X).
No flood-hazard analysis has been conducted in these areas, but a flood risk still exists. Flood insurance rates reflect the uncertainty of the flood risk. These areas are labeled with the letter D on the flood maps.