New maps show more Upper Midwest homes in flood zones

The Federal Emergency Management Agency, or FEMA, uses historical flood data to map which areas are likely to flood during a 100-year storm. And homeowners in those zones are required to carry flood insurance.

But new maps by the First Street Foundation show a significant number of homes outside of FEMA’s flood zones are also at risk of flooding. Across the Upper Midwest, the nonprofit found three-times as many homes may be vulnerable in a 100-year storm, according to an analysis of the maps by the Federal Reserve Bank of Minneapolis. And in Minneapolis, 37 times as many homes may be at risk.

Tu-Uyen Tran, a senior writer for the Minneapolis Fed, analyzed the maps. He said, unlike the FEMA maps, they take into account increasing rainfall due to climate change and consider smaller areas.

“A couple city blocks that are lower than other parts of the city, and let’s say rain overwhelms the drainage system, that area would flood,” he said. “But it would not appear as a high flood risk on FEMA’s flood map.”

Tran discussed the maps on Climate Cast. Hear the conversation using the audio player above or subscribe to the Climate Cast podcast wherever you get your podcasts.