Figure 1 – FIRM Panel

LOMR… Low what? A LOMR (LOW-mar) or a Letter of Map Revision is defined by FEMA as a “…modification to an effective Flood Insurance Rate Map (FIRM), or Flood Boundary and Floodway Map (FBFM), or both.” You may be familiar or have heard the term FIRM, FIRM panel, flood map or something similar get tossed around, and it would look something like Figure 1. FIRM panels were developed through the National Flood Insurance Program (NFIP), created by Congress in 1968, as an official map that delineates the Special Flood Hazard Areas (SFHA’s) for communities. Studies to develop the FIRM panels were initially done in the late 70’s and early 80’s. Many communities now have revised studies dating post 2000’s. It is important to understand that while the FEMA flood studies provide an invaluable resource for determining potential flood risk, there may be areas of the mapping that can be improved through a more detailed study. This is where the LOMR comes in.

A LOMR is the collection of more detailed data of the stream channel and the structures that cross it. This is where our brave and manly survey team here at Banning go out in the brush and gather detailed elevation data of channel cross sections, existing bridge, and crossing information to get an updated existing topography. This data can then be incorporated into the new Hydrologic and Hydraulic Model that is used to remap the SFHA’s. This remapping has the potential to remove areas on the FIRM panel from the SFHA’s which can be huge from a flood insurance and development standpoint. Residential or commercial property owners in your community may have the opportunity to reduce or remove certain flood insurance premiums; an area that was previously undesirable for development, may become more available. This mapping process can also be applied to streams or channels that do not currently have the SFHA’s delineated but need them identified in order for the community to responsibly plan for future development. Take a look at one of our more recent LOMR’s done for the Town of Danville in Figure 2. The magenta shows the area that was removed from the floodplain as a result of this study.

Figure 2 – Annotated FIRM Panel

Beware though, the LOMR process is not for the faint of heart. Not all areas are good candidates for this type of remapping, and the permitting process alone can take between 18 and 24 months. The bottom line is, there is a potential more detailed information and modeling could be beneficial to your community. Reach out to us here at Banning if you would like to discuss how we may be able to help.

P.S. Gold star to anyone that can point and tell me whose office is located in southwest quadrant of the FIRM Panel shown in Figure 1.

~ Max Kolb, PE, CFM



Max is a Project Manager in our Water Resources group and recently passed his PE exam. Banning has been his home for almost four years after completing his engineering degree from Florida Gulf Coast University.