FEMA data quality and map accuracy
The flood maps generated on this site may differ from other flood maps, including those published by FEMA because of several factors. These factors include, but are not limited to, differing methods for representing the earth’s surface two-dimensionally, and periodic changes to the flood data published by FEMA. Our maps use the most current flood data, which in many cases is more recent, and potentially more accurate, than the ones used for the official maps.
Publication date
PropertyShark’s FEMA flood maps are generated from digital source data published by FEMA. The publication date listed in our Property Reports is the date the data was published, and does not necessarily correspond to the publication date of any official FEMA flood map.
Assignment of properties to FEMA Flood Zones
Based on the maps we create from data provided by FEMA, PropertyShark has assigned properties to flood zones based on certain classification criteria, described below. Given the imperfections inherent in both the source data and in mapping technology, we offer no guarantees or warranties regarding the accuracy of this information.
Zone designations and classification criteria:
Major zones and sub codes:
Special Flood Hazard Areas (SFHA)
The land area covered by the flood-waters of the base flood is the Special Flood Hazard Area (SFHA) on NFIP maps. The SFHA is the area where the National Flood Insurance Program’s (NFIP’s) floodplain management regulations must be enforced and the area where the mandatory purchase of flood insurance applies. The SFHA includes Zones A, AO, AH, A1-30, AE, A99, AR, AR/A1-30, AR/AE, AR/AO, AR/AH, AR/A, VO, V1-30, VE, and V.
Zone A
Areas subject to inundation by the 1-percent-annual-chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone AE and A1-30
Areas subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone AH
Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually areas of ponding) where average depths are between one and three feet. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone AO
Areas subject to inundation by 1-percent-annual-chance 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 in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Some Zone AO have been designated in areas with high flood velocities such as alluvial fans and washes. Communities are encouraged to adopt more restrictive requirements for these areas.
Zone AR
Areas that result from the decertification of a previously accredited flood protection system that is determined to be in the process of being restored to provide base flood protection. Mandatory flood insurance purchase requirements and floodplain management standards apply
Zone A99
Areas subject to inundation by the 1-percent-annual-chance flood event, but which will ultimately be protected upon completion of an under-construction Federal flood protection system. These are areas of special flood hazard where enough progress has been made on the construction of a protection system, such as dikes, dams, and levees, to consider it complete for insurance rating purposes. Zone A99 may only be used when the flood protection system has reached specified statutory progress toward completion. No Base Flood Elevations (BFEs) or depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone V
Areas along coasts subject to inundation by the 1-percent-annual-chance flood event with additional hazards associated with storm-induced waves. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone VE and V1-30
Areas subject to inundation by the 1-percent-annual-chance flood event with additional hazards due to storm-induced velocity wave action. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.
Zone A takes precedence over Zone B; Zone B takes precedence over Zone C (X). Within each major zone, the subcategories are listed in rank order (i.e. V takes precedence over VE; VE takes precedence over A, etc.).
Moderate flood hazard areas:
Moderate flood hazard areas, labeled Zone B or Zone X (shaded) are also shown on the FIRM (Flood Insurance Rate Map), and are the areas between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood.
Minimal flood hazard areas:
The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded).
If a parcel intersects one or more flood zones all intersected values will be shown in the minireport/property-report of the property.
Additional information on flood zones:
FEMA’s Homepage:
FEMA’s Map Viewer
https://www.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd
Definitions of FEMA Flood Zone Designations:
https://www.fema.gov/flood-zones
https://www.floodsmart.gov/all-about-flood-maps
FEMA Flood Map Service Center : Search All Products: