Map Change Requests
Those who wish to challenge the accuracy of a FEMA Special Flood Hazard Area (SFHA) and want a Flood Insurance Rate Map (FIRM) amended or revised can do so by submitting a map change request to FEMA.  Such a request must be accompanied by sufficient evidence refuting the accuracy of the SFHA.  [Note that merely arguing that it has never before flooded at a particular location is not considered sufficient evidence.]

The most common challenge to the accuracy of a SFHA is that of its boundaries, which more often than not have been derived from imprecise topographic data.  If one can demonstrate that the lowest adjacent grade to a structure that is included in a SFHA is actually higher than the base flood elevation defined at that location (thereby proving the structure should be outside of the SFHA boundary), then FEMA will remove the structure from the SFHA by issuing a letter of map amendment.

Letter of Map Amendment (LOMA)
A LOMA is a descriptive amendment to a FEMA Flood Insurance Rate Map (FIRM) identifying parcels and/or structures that are considered outside of a Special Flood Hazard Area (SFHA) regardless of what the FIRM may show (i.e., the delineated boundaries on the map are not immediately revised).
For a structure to qualify for removal from a SFHA using FEMA's standard methodology, the lowest grade adjacent to the structure must be at least as high or higher than the Base Flood Elevation (BFE).

Brief descriptions of common SFHAs are provided below.

Zone A
A "Zone A" flood zone is an approximate Special Flood Hazard Area created without a detailed study.  Consequently, there are usually no Base Flood Elevations provided.  For a structure to qualify for removal from an "A" zone, a BFE at the property must first be derived.

Zone AE
An "AE" zone represents riverine flooding in a detailed study area.  Cross-sections drawn through the SFHA at occasional intervals indicate approximate BFE levels rounded to the nearest whole-foot.  The BFE at any particular property in an "AE" zone must be derived to the nearest tenth-of-a-foot using a stream channel profile provided in the community's Flood Insurance Study.

Zone AH
An "AH" zone represents an area of shallow ponding.  The BFE at all properties within the ponded area is indicated on the FIRM.

Zone AO
An "AO" zone represents an area of shallow flood flow having an average depth of one, two, or three-feet as defined by the Base Flood Depth (BFD) shown on the FIRM.  The applicable BFE at a particular property must be derived from the BFD and certain characteristics of the property and the SFHA.