Land records · Parcel maps · October 6, 2026
What Is a LOMR? Letter of Map Revision Explained
What is a LOMR? A Letter of Map Revision is FEMA's official change to a flood map based on new data or projects. How it differs from a LOMA and LOMR-F.
What is a LOMR? A Letter of Map Revision, or LOMR, is FEMA’s official revision to an effective Flood Insurance Rate Map. It changes flood zones, base flood elevations, floodways, or other map features based on new technical data, such as updated hydrology, better topography, or completed projects like levees, channels, or bridges. A LOMR becomes part of the effective map without FEMA reprinting the whole panel. This page is general land-records background, not legal advice.
LOMR vs LOMA vs LOMR-F
| Letter | What it does | Typical use |
|---|---|---|
| LOMA | Removes a property or structure from the special flood hazard area based on natural ground elevation | Single lots or buildings |
| LOMR-F | Removes a property from the floodplain because fill raised it | Lots elevated with fill |
| LOMR | Revises the map itself based on new data or projects | Streams, subdivisions, flood control projects |
| CLOMR | Conditional approval before a project is built | Developers, communities |
See what is a LOMA.
Who requests a LOMR
LOMRs are usually requested by communities, developers, or engineers. The application includes engineering analyses, survey data, and certifications. Fees apply for many requests. Individual homeowners more commonly use a LOMA or LOMR-F.
The process
- A community or engineer prepares a technical submission.
- FEMA reviews the data.
- If approved, FEMA issues the LOMR with revised map panels or annotations.
- A public notice and appeal period follows for changes to BFEs.
- The LOMR becomes effective, often after a waiting period.
CLOMR first
Before building a project that will change flood risk, such as a new bridge or fill in a floodplain, developers often get a Conditional LOMR. It shows FEMA would revise the map if the project is built as designed. After construction, an as-built LOMR finalizes it.
Effects on property owners
A LOMR may move properties into or out of flood zones or change BFEs. That affects insurance requirements and building rules. Lenders use the current effective map including LOMRs to decide whether flood insurance is required.
Finding LOMRs
FEMA’s map service center lists LOMRs and other letters by community and map panel. Local floodplain administrators keep copies. A LOMR may not show on older printed maps, so always check for letters affecting a panel.
Using LOMRs with maps
When reading a flood map, check the panel date and any LOMRs issued after that date. The LOMR controls for the area it covers. See how to read a FEMA flood map.
How long a LOMR takes
A LOMR is not quick. FEMA’s review of a technical submission commonly takes several months, and requests that need more data can take longer. When the revision changes base flood elevations, there is also a public notice period, often published in a local newspaper, followed by a 90-day appeal period before the change takes effect. Property owners waiting on a LOMR for insurance purposes should keep their current policy in force until the revision is effective, since the old map controls until then.
When a homeowner might be affected
Even if you never request a LOMR, one can change your situation. A city that builds a new detention pond, or a developer that regrades a creek for a subdivision, may obtain a LOMR that shrinks or shifts the floodplain nearby. If your lender sends a letter saying flood insurance is now required, or no longer required, ask which map panel and which letter the determination relies on. If you think the determination is wrong, the lender’s flood zone vendor and the local floodplain administrator can help you check it.
Bottom line
A LOMR is FEMA’s official revision to a flood map based on new technical data or completed projects. It differs from a LOMA, which removes a single property based on elevation, and a LOMR-F, which addresses fill. Check for LOMRs when reading a flood map panel. Find county flood map layers via the Platbookmapper map.
What is a lomr FAQ
What does LOMR stand for?
Letter of Map Revision.
What is the difference between a LOMA and a LOMR?
A LOMA removes a property based on its elevation; a LOMR changes the flood map itself.
Who can request a LOMR?
Usually communities, developers, or engineers with technical data.
What is a CLOMR?
A conditional approval showing FEMA would revise the map if a proposed project is built.
How do I find LOMRs for my area?
Check FEMA’s map service center or ask the local floodplain administrator.