As the Federal Emergency Management Administration (FEMA) transitions into the next phase of its ambitious effort to improve its assessment of flood risk across the country, builders are pondering what impact the government’s effort is going to have on the availability of land for future residential development.

Property owners in several markets are already complaining about the accuracy of FEMA’s updated flood maps and how their local implementation would force more homeowners and businesses to buy flood insurance, and could also stymie development and even renovation of existing structures. However, others—including a spokesman for NAHB—suggest that more sophisticated mapping and risk assessment could ultimately benefit homebuyers, builders, and developers by giving them a much clearer picture about a given market’s relative flood hazard potential.

This year, FEMA is wrapping up its six-year-long Flood Map Modernization Program, for which Congress appropriated more than $800 million. These maps are used by the federal government to set rates for its National Flood Insurance Program, which homeowners and businesses in high-risk areas use to purchase lower-priced insurance policies. In many markets, floodplain maps hadn’t been updated in 30 years. New technology is allowing FEMA to better identify those high-risk areas where there is at least a 1% annual chance of flooding. (In such markets, lenders almost always require borrowers to take flood insurance.) The maps are digitized so their geo-spatial data can be used with local Geographic Information Systems. Eventually all of the maps will include new floodplain boundary standards.

This modernization, when completed, will provide more reliable digital flood hazard data and maps for 92% of the nation’s population, as well as easier access to that data, FEMA says. “FEMA’s top priority is the safety of the communities we serve, and an important part of our commitment to protect lives and property is ensuring that people are aware of the natural hazards and risks that exist in their communities,” says the agency’s spokesman Clark Stevens. 

Alan Lulloff, science services program manager for the Association of State Floodplain Managers in Madison, Wis., says there has been widespread support for this effort because the old maps “were difficult to use, from a cartographic standpoint, and had gross errors,” which made land-use applications of the maps “harder to enforce.” The new maps also match local topographies better, he tells BUILDER.

Indeed, mapping flood-hazard areas with greater precision is placing more structures within floodplains in many markets. For example, new flood maps raise flood elevations in Mecklenburg County, N.C., by eight feet. Newsday reported on Tuesday that 25,000 more residents on Long Island, N.Y., would need to purchase flood insurance as a result of the remapping of Nassau and Suffolk counties. New maps for Sioux Falls, S.D., increase the number of homes in the floodplain there to 2,600, from 800, according to local news reports. A new floodplain map for the village of Sabina near Wilmington, Ohio, would add 100 homes if the adoption of those maps becomes law next April 10.

The new maps are also removing homes and businesses from floodplains, which is what happened for more than 4,700 homes on Long Island. Lulloff says his organization recently did a risk analysis in Wisconsin, and found that the number of homes included and excluded in floodplains by new mapping “was pretty much a wash.”

Still, homeowners and businesses in some markets are pushing back against the new map data. The Morning Sentinel in Portland, Maine, reports that the state’s two U.S. senators and one of its members of congress are urging FEMA to review its updated map which reclassifies Portland Harbor as a “V-zone,” meaning that high velocity waters could cause structural damage during a 100-year flood. In V-zones, new structures can’t be built on piers or wharves over water, and existing structures can’t be substantially rebuilt if damaged or destroyed. Penny St. Louis Littell, Portland’s city planning director, told the newspaper that she believes the new regulations are intended to curb residential development in environmentally sensitive areas, and shouldn’t be applied to a densely-built harbor area such as Portland's.

Probability and Risk

Map modernization has been the first step in FEMA’s broader Risk MAP (for Mapping, Assessment and Planning) program, which was approved last March, and has received congressional appropriation through 2014. Working with state, local and tribal entities, FEMA’s objectives include using such factors as projections about climate change or population shifts to determine the likelihood of an area’s flooding. Lulloff says the goal of this effort “is to make sure the maps are equitable and fair, to make sure they show where the hazards are, and to do a better job of showing the relative degree of hazard.”

Neither Lulloff nor Ken Ford, who manages NAHB’s disaster assistance and mitigation program, would speculate about the extent to which the Risk MAP program might impede future development. At the very least, says Lulloff, “it’s important for people to know where the hazards are so they can make conscious decisions about where to build and live.” Ford concedes that FEMA’s effort “could very well lead to changes” in how land is developed and built upon. But that’s not necessarily a negative for builders, he adds, noting that homes built to new flood elevations standards would be much easier to sell and resell than existing homes that don’t comply.

FEMA’s maps and risk assessment are also taking into account re-evaluations of the country’s aging levee system by the Army Corps of Engineers. When the Corps decertifies a levee, FEMA has been removing that barrier from its maps, which means towns and cities protected by that levee are suddenly in a floodplain. The Stockton Record reports that nearly 40,000 residential and commercial structures in California’s San Joaquin Valley would be designated as “high risk” if levees there lose their status. About 150,000 property owners in the St. Louis area could be required to buy flood insurance unless three counties can come up with the $450 million needed to repair Mississippi River levees.

The Obama Administration has drafted an Executive Order that would require federal agencies that own or manage properties to “identify and mitigate effects to minimize potential loss of life from flooding or adverse effects to natural resources.” The order promotes “nonstructural approaches” to mitigation. Lulloff explains that the order primarily would cover “critical infrastructure,” like highways and nuclear power plants, which might be at risk from a 500-year flood occurrence, and where he says the application of higher flooding thresholds would be reasonable.

But Ford says NAHB is worried enough about the implications of the order on future residential development that it is in the process of formulating a response to it, which might include “reaching out to the White House.”

John Caulfield is senior editor for BUILDER.

Learn more about markets featured in this article: Washington, DC, Portland, ME.