O'Brien County, IA: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, O'Brien County scores at the 18.5th percentile for flood hazard, rated "Very Low" — among the lowest flood hazard in the country. 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 1.5 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
23.5% of the homes FEMA requires to carry flood insurance in O'Brien County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 4 policies against 17 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.1% of all residential structures in O'Brien County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How O'Brien County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, O'Brien County ranks 2600 — 1 being the highest hazard nationally — and 2141 by population among all 3144 counties covered here, where 1 is the largest. O'Brien County, Iowa is home to about 14,260 people across 573.035 square miles of land.
What to do next if you own or are buying in O'Brien County
5 of O'Brien County's 7,137 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where O'Brien 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.