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From time to time, the Federal Emergency Management Agency (FEMA) reviews and makes adjustments to the official Flood Insurance Rate Maps (FIRMs) published for a community. Modifications to the maps are made when changes in flooding conditions occur in a particular area. Such changes result from newly constructed flood improvements, as in the case of the Lower Santa Cruz River Levee, but also may arise following major flood events and other changing conditions.

Example of area removed by LOMR on DFIRmSome approved LOMRs, CLOMRs and LOMAs are available for download.

There is one type of conditional map revision, and two types of actual map revisions.

Letter of Map Revision (LOMR)

A LOMR is an official revision to the Flood Insurance Rate Maps (FIRMs) issued by the Federal Emergency Management Agency (FEMA). LOMRs reflect changes to the 100-year floodplains or Special Flood Hazard Areas (SFHA) shown on the FIRMs. In rare situations, LOMRs also modify the 500-year floodplain boundaries. Generally speaking, LOMRs are used for multi-lot projects and large scale changes in FEMA floodplains. Changes may include modifications to Base Flood Elevations, floodplain widths, and floodways. The LOMRs are issued after a floodplain has been remapped due to a major flood event, after better mapping data becomes available, or after structural flood control improvements have been installed.

Conditional Letter of Map Revision (CLOMR)

A CLOMR is similar to a LOMR (see above), but is based on proposed conditions and does not change the FIRMs. A CLOMR is the method used by FEMA to let people know that projects, if constructed per the design submitted to and approved by FEMA, revision of the FIRM panel with a LOMR is likely. For example, a CLOMR might be obtained by a developer who is modifying a floodplain through the use of constructed drainage infrastructure. Design drawings are submitted to FEMA showing the existing, pre-developed floodplain conditions and the proposed floodplain conditions after planned development. If FEMA approves the CLOMR, the developer can be reasonably sure that a LOMR for the project will be approved upon completion of the drainage infrastructure that alters the floodplain.

Letter of Map Amendment (LOMA)

A LOMA is generally used for single-lot modifications to the floodplain, or to remove individual structures from the floodplain, without actually modifying the floodplain delineation on the FIRM. LOMAs are typically used to remove the flood insurance requirement for a particular structure or for structures on a particular parcel. There are two types of LOMAs, those for properties and those for structures. Property LOMAs remove an entire parcel or a portion of a parcel outside of the floodplain. These LOMAs require a survey of the property to demonstrate what portions of the property are above the base flood elevation. Structure LOMAs remove only the structure itself from the floodplain, and are the easiest types of LOMAs to obtain. These LOMAs only require a survey to demonstrate that the ground immediately adjacent to the structure is above the base flood elevation. If the footprint of the structure is expanded, a structure LOMA does not apply to the additional footprint unless another LOMA is approved.

We have also prepared a Frequently Asked Questions (FAQ) handout that provides background information about LOMRs, help with reading new FEMA maps, and more.