FEMA Updates Floodplain Maps

 Tom Larson  |    February 08, 2009

The Wisconsin Department of Natural Resources (DNR), in conjunction with the Federal Emergency Management Agency (FEMA), is in the process of revising the floodplain maps for all 72 counties in Wisconsin. The new floodplain maps could have an impact on flood insurance as well as the use and value of affected property, and could present challenges for both property owners and REALTORS®.


Floods are the most common natural disaster in the United States, and Wisconsin ranks 10th in the nation for documented flood damage. In Wisconsin, the primary cause of floods is excessive rain, snowmelt or a combination of the two. Floodplains are typically lowland areas adjacent to lakes, wetlands and rivers that are covered by water during a flood. However, many of Wisconsin’s flood-prone lands are simply low-lying areas or depressions where water naturally collects after rain.

A floodplain map determines whether a structure is in a floodplain and whether or not the owner of a structure will need to purchase flood insurance. Unfortunately, many of these maps are outdated or inaccurate due to urban growth, changes to river flows and shorelines, and flood mitigation efforts like dams and levees. In fact, nearly two-thirds of Wisconsin’s floodplain maps are at least 10 years old. Moreover, many of the existing floodplain maps were created using 10-foot-contour intervals, which have proven to be inaccurate in determining a property’s flood risk.

To remedy this problem, FEMA has launched a multi-year national Map Modernization Plan — an effort to redraw the maps that predict where major floods are likely to occur. The updated maps will help support floodplain management and sound flood insurance decisions, such as determining who needs flood insurance, calculating flood insurance rates and ensuring that new development will be safe from flooding.

Map updating effort 

Beginning in 2003, FEMA, in conjunction with the DNR, began updating maps throughout Wisconsin with the goal of completing 54 counties by 2010. So far, 23 counties, including their cities and villages, have gone through FEMA’s map modernization process and are updating floodplain ordinances to include new maps. These counties include: Adams, Barron, Buffalo, Burnett, Calumet, Clark, Columbia, Dane, Door, Eau Claire, Fond du Lac, Green, Green Lake, Jefferson, La Crosse, Milwaukee, Ozaukee, Portage, Rock, Sheboygan, St. Croix, Walworth and Waukesha. 

The new mapping has resulted in reduced flood risk for some properties and the removal of other properties from the mapped floodplain entirely. However, the flood mapping process has also added some properties to the floodplain. Unfortunately, some property owners first discover that their property is located in the floodplain during a sale or transfer of property. This can present problems for property owners because structures located in a floodplain may trigger one or more of the following:

  • Flood insurance is required for any structure located in special flood hazard areas as a condition of any mortgage from a federally insured or regulated lender.
  • Structures not in compliance with current floodplain regulations are subject to the 50-percent rule, which can place significant restrictions on the ability to improve or expand a structure.
  • Different development standards exist for new structures in the “flood fringe” — the area outside of the floodway where standing water is often present. 

Requested changes to floodplain maps 

If a property owner believes that a property has been erroneously added to a floodplain, the property owner has two options for seeking a change. First, if the property owner discovers this error during the required public notice period immediately after the map is finished, the property owner has 90 days to appeal. All appeals must (a) be submitted through the community in which the property is located, and (b) demonstrate that the flood hazard determinations are scientifically or technically incorrect.

Second, if the property owner discovers this error after the 90-day appeal process is over, the property owner may request an official revision to the floodplain map known as a letter of map amendment change (LOMC). An LOMC is issued in place of the physical revision and republication of the affected map. There are two types of LOMCs — a letter of map amendment (LOMA) and a letter of map revision (LOMR). An LOMA is a correction to a flood map and can be obtained by submitting mapping and survey data showing that a property’s natural lowest grade is above base flood elevation. An LOMR is a correction to a flood map based upon technical engineering studies and thus is typically used for complex or large-scale projects.

Accurate floodplain maps are critical sources of information for local communities, property owners and REALTORS® who sell property in or adjacent to floodplain areas. Accordingly, REALTORS® and property owners should be aware of floodplain mapping efforts in their respective counties and review the revised maps closely to ensure they are accurate.

Tom Larson is Director of Regulatory and Legislative Affairs for the WRA. 

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