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Floodplains

Floodplains are normally dry or semi-dry land areas to which water naturally flows as water levels rise. Floodplains are typically found near rivers, lakes and the coast; however, many of Wisconsin's flood-prone lands are simply low-lying areas or depressions where water naturally collects when it rains.

Accurate floodplain maps are critical for REALTORS® who sell property in or adjacent to a floodplain. These maps determine whether or not a structure is in a floodplain and whether or not a structure will need to purchase flood insurance. Unfortunately many of these maps are outdated or inaccurate. (Note: beginning in 2003, FEMA -Federal Emergency Management Agency - began updating maps throughout the state with the plan to have 54 counties completed by 2010. To check on the status of your county, go to http://dnr.wi.gov/org/water/wm/dsfm/Flood/documents/status.pdf.)

REALTORS® should be very careful not to make representations or determinations about floodplain property and should direct buyers and sellers to a local surveyor or the Wisconsin Department of Natural Resources (DNR) for more information.

What To Look For

The following information may be helpful for buyers who are looking to purchase property that may be located in a floodplain area:

a. Wetlands on or near the property are clear indications that water stands in the area. Looking at a cypress tree "buttress," water will normally rise two-thirds of the buttress. Also look for water marks on trees.

b. If there are lakes, streams or rivers nearby, find out what the established 10-year, 25-year and 100-year flood elevations are. Will these water levels extend onto the property? Where are these elevations in relation to the floor slab, septic tank, other buildings, driveway, access roads and other permanent features of the property? If these areas flood, what problems will it cause? Will emergency vehicles be able to reach you during a flood? Remember, lakes and other water bodies fluctuate naturally; some of them can vary by several feet each year or over the course of several years. This natural fluctuation could cause flooding or standing water on surrounding lands.

c. Where are the floorslab, access roads and other permanent features of the property in relation to the surrounding ground? Are they at the bottom of a hill or in a depression? Remember, water flows downhill and will collect there unless there is someplace else for it to go.

d. Does the property or subdivision have a stormwater collection system, either drainage ditches or stormwater sewers? If not, where does storm water flow?

e. Property away from the coast is susceptible to flooding caused by rain, rapid snow melt or ice jams causing high water levels in lakes or rivers, or overwhelming stormwater management systems.

f. "What is the elevation of this property?" For the exact elevation for the house slab, contact an independent surveyor. For the elevation of an area, the United States Geological Service (USGS) has aerial contour maps that cover the majority of the Wisconsin's 72 counties.

g. "Where are the nearby lakes, and what are their mean annual, 10-, 25-, and 100-year flood elevations? How does this relate to the property's elevation?" The local county building, planning or zoning department may have this information - otherwise, call the DNR.

h. "Where are the nearby rivers and streams, and what are their flood stage elevations? How does this relate to the property's elevation?" The local county building, planning or zoning department may have this information. The DNR does not use the term "flood stage elevations". That is phrase used by the Weather Service and the USGS and is the height of the water in feet in from the bottom of the stream. The DNR uses the term "flood elevation" which is the height of the 1% chance flood in relation to the National Geodetic Vertical Datum, 1929 (NGVD) or the North American Vertical Datum, 1988 (NAVD) - these are newer and more exact ways of saying Mean Sea Level. If someone calls the DNR to get information regarding flood stages, the DNR will not be able to give them any information.

i. "What type of soils are in the area?" Some soil types are indicative of a wetland area. If the property is in a subdivision where much of the original land was cleared, a soils map would show the original soil type. Check with the local office of the U.S. Department of Agriculture's Natural Resources Conservation Service (formerly known as the Soil Conservation Service) or Wisconsin's Department of Agriculture Trade and Consumer Protection (DATCP) for a soils map of the area. The local county building, planning or zoning department may have this information. An environmental consulting firm could also conduct a soils test for a nominal fee.

j. "What FEMA Flood Zone is the property located in?" Ask the local building, planning or zoning department, or your insurance company. Your REALTOR may also know. Remember the mandatory purchase of flood insurance is required if the structure is located in a Special Flood Hazard Area which are called A or V zones on the Flood Insurance Rate Map..

k. If there is a structure on the property, "What percentage of the structure's market value has already been accrued toward substantial improvement?" it is important to explain the 50 percent rule because the floodplain one is different from the shoreland one. In floodplains, if the cost of all structural improvements since the date the community joined the NFIP equals or exceeds 50 percent of the structure's equalized assessed value then the structure must meet the land use and building requirements of a new structure. For a damaged structure, if the cost of repairing a structure damaged by any cause equals or exceeds 50 percent of the structure's equalized assessed value then the structure must meet the land use and building requirements of a new structure.

Floodplain Information

DNR Estimated Timeline Map  

Floodplain zoning, Management and Grant Opportunities - For Local Communities

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