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Health, Science, Environment

Missouri And Illinois Have More Flood-Prone Properties Than FEMA Estimates, Study Finds

Employees of O'Dell's Irish Pub & Ale House in Eureka climb over a wall of sandbags to get into the bar Thursday afternoon.
Carolina Hidalgo | St. Louis Public Radio
A national study from a consortium of academic researchers has found that about twice as many properties in Missouri and Illinois are at risk of flood damage than federal agencies estimate.

More than 280,000 properties in Missouri are at risk of flood damage, according to a nationwide study of flood zones.

That's nearly twice the number estimated by the Federal Emergency Management Agency, say researchers for the First Street Foundation, a consortium of academics. They calculated the higher figure after considering the effects of climate change and parts of the state not included in FEMA's flood insurance maps.

In Illinois, 451,700 properties are at risk of flood damage, or more than twice the number FEMA estimates.

The New York-based nonprofit research group found that over the next three decades, the number of homes and businesses at risk of flood damage in Missouri could increase by 1.8%, or 5,200 properties. 

The actual number of properties at risk could be much higher if researchers better accounted for floodplain development and changes to rivers to accommodate navigation, said David Stokes, director of the Great Rivers Habitat Alliance. 

“The real flood risk is higher than people are led to believe,” Stokes said. “This report is so focused on climate change that it’s understating the areas where flood risk is increasing for other reasons.” 

The report found that St. Louis has more than 13,000 properties that are at risk of flood damage and that by 2050, another 500 properties could be vulnerable. 

Researchers also calculated that a third of properties in the city of Valley Park could be at risk of flood damage. But city officials disagree. The report does not make any reference to the city’s large levee, which has kept residents dry during three recent major floods along the Meramec River, City Attorney Tim Engelmeyer said.

“I just don’t know where or how they’re coming up with that number considering that the most flood-prone area for the city of Valley Park is protected by a levee that performed up to a 500-year standard during the last flood,” Engelmeyer said. “I don’t know how they’re coming up with 33%. That’s way, way too high.” 

Property values in Valley Park have increased since the levee was built in 2005, Engelmeyer said. After a record-breaking flood damaged communities along the lower Meramec River in 2015, scientists and environmentalists suspected that the city’s levee was built too high and pushed floodwaters to neighboring communities. 

The federal flood insurance maps do not conflict with First Street Foundation’s findings, a FEMA spokesperson said.

A 2015 study from Washington University geologist Bob Criss concluded that federal agencies were underestimating the risk of major floods in the Midwest. The report found that FEMA and the U.S. Army Corps of Engineers were not adequately considering the effects of levees, dams and other manmade structures that can raise the risk of flood damage to downstream communities. 

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