Understanding LOMA and LOMR Map Revisions

In the world of flood insurance, the Flood Insurance Rate Map (FIRM) is the definitive document used by lenders, insurance agents, and property owners to determine flood risk. However, because these maps are often created using broad topographical data, they may not always reflect the precise elevation of an individual property or structure. To address these inaccuracies, the Federal Emergency Management Agency (FEMA) established the Letter of Map Change (LOMC) process.

Understanding the distinctions between different types of map revisions is a critical component of the complete Flood exam guide. These administrative procedures allow for the official amendment or revision of a FIRM, potentially removing the mandatory purchase requirement for flood insurance. The most common forms of LOMC are the Letter of Map Amendment (LOMA) and the Letter of Map Revision (LOMR).

A Letter of Map Amendment (LOMA) is an official document from FEMA that amends the FIRM by removing a specific property or structure from a Special Flood Hazard Area (SFHA). A LOMA is typically issued when a property owner can prove that their land or building was inadvertently included in a high-risk zone (such as Zone A or AE) despite being on natural ground that is at or above the Base Flood Elevation (BFE).

To qualify for a LOMA, the following criteria must generally be met:

• The land must be natural ground (not elevated by fill material).
• The Lowest Adjacent Grade (LAG) of the structure must be at or above the BFE.
• The property owner must submit technical data, usually in the form of an Elevation Certificate, to support the request.

When a LOMA is granted, the property is officially re-designated as being in a moderate-to-low risk zone (such as Zone X). This change eliminates the federal mandatory purchase requirement for flood insurance, though lenders still retain the right to require it as a matter of private policy.

While a LOMA applies to natural ground, a Letter of Map Revision Based on Fill (LOMR-F) is used when a property has been elevated above the BFE through the placement of earthen fill. Because the topography has been physically altered by human activity, FEMA requires a different administrative process than the standard LOMA.

For a LOMR-F to be issued, the community must certify that the fill meets specific engineering standards and does not obstruct the flow of floodwaters or cause drainage issues for neighboring properties. Like a LOMA, a successful LOMR-F removes the mandatory purchase requirement, but it involves a processing fee and more rigorous community oversight. Students should practice identifying these distinctions using practice Flood questions to ensure they understand when fill material changes the application type.

A Letter of Map Revision (LOMR) is a more comprehensive change than a LOMA or LOMR-F. While LOMAs and LOMR-Fs usually apply to individual parcels or buildings, a LOMR is used to update the FIRM across a larger area or community. This is often necessitated by physical changes that alter the flood risk of a whole neighborhood or reach of a river.

Common reasons for a LOMR include:

• Construction of a new levee or floodwall.
• Bridge or culvert construction/replacement.
• Channelization or realignment of a stream or river.
• Improved hydrologic or hydraulic modeling that more accurately defines the BFE.

Because a LOMR changes the actual flood zones, BFEs, or floodway boundaries on the map, it requires extensive engineering data and a public notice period before it becomes effective.