The National Flood Hazard Layer (NFHL) dataset represents the current effective flood data for the country, where maps have been modernized.  It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Revision (LOMRs). The NFHL is updated as studies go effective. For more information, visit FEMA's Map Service Center (MSC).  

The default base map conforms to FEMA's specification for horizontal accuracy. This map should be considered the best online resource to use for official National Flood Insurance Program (NFIP) purposes when determining locations in relation to regulatory flood hazard information.  If a different base map is used with the NFHL, the accuracy specification may not be met and the resulting map should be used for general reference only, and not official NFIP purposes. For FEMA’s policy on the use of digital flood hazard data for NFIP purposes see Standards for Flood Risk Products.