Flood Maps: What Communities Need to Know

By Jayme Breschard Thomann, Senior Planner, AICP, CFM Genesee/Finger Lakes Regional Planning Council
Record-breaking rain inundated 20 parishes in southeastern Louisiana in August 2016, resulting in 13 deaths across the state, 60,000 damaged homes, and an estimated $30 million in flood costs so far. The devastating flood in Louisiana is now the worst natural disaster to strike the United States since Hurricane Sandy four years ago. According to the Federal Emergency Management Agency (FEMA), an estimated 42 percent of homes in high-risk areas have flood insurance. Only 12.5 percent of homeowners in low and moderate-risk zones do. Unfortunately, many of the areas hit hard by record rainfall were not considered at high-risk for flooding.

The National Flood Insurance Program (NFIP) was created in 1968 by Congress to help people financially protect themselves from flooding. The NFIP offers flood insurance to homeowners, renters, and business owners if their community participates in the NFIP and enforces floodplain management regulations. These regulations include minimum construction requirements in the Special Flood Hazard Area (SFHA), which are shown on a community's Flood Insurance Rate Map (FIRM). Structures in the SFHA with mortgages from federally regulated or insured lenders are required to have flood insurance. Flood insurance is not typically required in low-to-moderate flood risk areas. However, people outside of mapped high-risk flood areas file over 20 percent of all NFIP flood insurance claims and receive onethird of Federal Disaster Assistance for flooding.

Which brings us back to the current state of affairs in Louisiana—about 16,311 of the 137,616 homes in Baton Rouge had flood insurance, or about 11.9 percent total. Most of the flooding in East Baton Rouge Parish—and the areas FEMA flood maps consider most at risk—is  outside the city, however. That is compared to 14 percent of the 56,800 homes in Lafayette and 39.1 percent of the 154,804 homes in New Orleans. So, are FEMA's flood maps inaccurate? Why do residents not have flood insurance?

First, let's define a “high-risk flood area.” Flood risk zones are determined by FEMA on a community's FIRM. “A Zones” are high-risk flood areas that are subject to inundation during a 100-year flood, which is the flood elevation that has a 1-percent chance of being equaled or exceeded each year. Along with “V Zones”—which applies in coastal situations with additional hazards associated with storm-induced waves—A Zones are defined as the SFHA on a community's FIRM. Low-to-moderate flood risk areas are subject to the 500-year flood, which means a flood of that size or greater has a 0.2-percent chance (or 1 in 500 chance) of occurring in a given year. They are shown on the FIRM as B, C, or X Zones (or a shaded X). FIRMs are usually on file at municipal offices. Maps are also available online or by writing, calling, or faxing a request to the FEMA Map Assistance Center.

Structures located in high-risk flood areas with mortgages from federally regulated or insured lenders are required to have flood insurance. Flood insurance is technically not required if the structure does not touch the floodplain—even though the parcel does. Still, the lending institution has the right to require a flood insurance policy. Coverage, however, is not heavily policed. And if you own a home outright, you cannot be forced to purchase coverage. Federal flood insurance is separate from homeowner policies. Many homeowners and renters mistakenly believe their standard
policies include flood damage. The combination of misinformation about what homeowner's insurance covers, residents “gambling” with coverage because they either can't afford it or the institutional memory of a disaster is short, and the fact that many flood maps no longer reflect current risks (due to land development and changes in the environment) tells the daunting story that flood risk is severely underestimated across the country.

Organizations like the Association of State Floodplain Managers (ASFPM) and its state chapter, the New York State Floodplain and Stormwater Managers Association (NYSFSMA), provide training and education on various floodplain management issues, including flood mapping and insurance, as does FEMA through online resources such However, the question about inaccurate or out-of-date flood hazard maps remains. For instance, the image below shows the status of FIRMs in New York State. For the nine-county Genesee-Finger Lakes Region (Genesee, Livingston, Monroe, Ontario, Orleans, Seneca, Wayne, Wyoming and Yates Counties), only one of the nine
counties has “modernized” maps: Monroe County. The remaining counties have access to paper maps—many dating to the 1970s and 1980s. As one can imagine, the development that has occurred over time in these communities—creating impervious surfaces such as roads, parking lots, and rooftops—has redirected the natural infiltration of precipitation and decrease to groundwater; increasing the amount of water entering the drainage network. Impervious surfaces increase
peak stream flows during storms because water runs off pavement and rooftops very quickly. Thus, the flood zones that were mapped in the 1970s and 1980s may have shifted and moved over the past forty years; structures that are mapped as “low and moderate-risk” may now be at high-risk and vulnerable to flooding.

Map modernization is the process by which more reliable and up-todate flood data is created by using the latest mapping technology and delivering it in a geographic information system (GIS)-based format. As a result, digital maps can be more accessible and updated easily and at less cost, as flood risks change. While many communities across
the country are still forced to use paper flood maps, organizations like ASFPM are continuing to advocate for funding to the national mapping program in order to accurately portray the national flood risk and bring attention to the nation's costliest hazard. New York State has also developed the Floodplain Mapping Program to aid FEMA's Flood Hazard Mapping. The State's preliminary floodplain maps and mapping status updates are available via the FEMA Region Support Center (RSC) website:

Local governments and emergency responders should locate their official flood maps and take advantage of tools to better understand flood risk. Regional Planning Councils (RPC) may be able to help—for close to 30 years, the New York State Association of Regional Councils (NYSARC) and the New York State Department of Environmental Conservation (DEC) have worked together to enhance, restore, preserve and protect the water resources of New York State. To find your nearest RPC, go to: And consider joining the NYSFSMA to access a multidisciplinary exchange in floodplain and stormwater management.