Story County, IA: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Story County scores at the 69.1th percentile for flood hazard, rated "Relatively Low" — below the national norm for flood hazard. The hazard here is driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 2.7 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Who actually carries the flood insurance FEMA requires
Out of 568 homes FEMA counts inside Story County's mapped flood zone, 43 carry the flood policy federal law requires there — 7.6% compliance, short of full coverage. Looking beyond the mandated zone, 0.3% of all residential structures in Story County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Story County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Story County ranks 1012 — 1 being the highest hazard nationally — and 609 by population among all 3144 counties covered here, where 1 is the largest. About 102,498 people live in Story County, Iowa, spread over 572.545 square miles.
What to do next if you own or are buying in Story County
Across all of Story County's 34,139 residential structures, 95 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Story County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. If you're unsure why any of this insurance requirement exists at all, the SFHA explainer covers it from first principles.