Millions More American Homes at Risk of Flooding than Previously Thought

Graphic: CNN

An alarming new analysis from the First Street Foundation revealed that millions of American homes are at a growing risk of extreme flooding.
As CNN wrote, today, around 8.7 million properties are located in Special Flood Hazard Areas as determined by FEMA’s flood maps, the legal standard used in the US to manage floodplains, determine insurance requirements and price policy premiums.
  • But as many as 14.6 million properties — nearly 70% more than are in FEMA’s Special Flood Hazard Areas — may actually be at significant risk of flooding.
  • The discrepancy between FEMA’s maps and this new data means that some 6 million property owners could be unaware of their current flood risk.

Why This Matters: FEMA’s flood data doesn’t account for many counties across the United States and in about 3,300 communities, the flood maps are more than 15 years old. We wrote last week that climate change will make it so that millions of Americans could lose access to the 30-year mortgage. This new flood data will make those assessments, along with which homes are uninsurable easier to determine. It’s also why we need a national climate service to regularly assess these risks for all Americans. Homeowners and renters must have easy access to data outlining the risks they’re facing.

Go Deeper: You for your home’s flood risk at

FYI: As Axios wrote, plans to integrate the data soon on its website, though it doesn’t have a specific launch date yet, a spokeswoman said Sunday.

The Discrepancy: First Street’s data was much more granular than FEMA’s and yielded a far different picture of national flood risk. As FEMA said in a statement, its maps are intended for floodplain-management and emergency-response decisions.

“The FEMA Flood Insurance Risk Maps and First Street Foundation maps do not conflict with each other, rather they complement one another by depicting different types of risk,” FEMA said. “Users should explore the differences between the maps to build a more comprehensive understanding of flood risk

Graphic: CNN

A Growing Flooding Risk: Climate change is causing more extreme precipitation and a growing risk of flooding in inland areas. This is in addition to increasing coastal flooding as a result of sea-level rise. Communities must prepare for these threats and take the science seriously–as not all do.

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