Riley County, KS: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Riley County scores at the 59.9th 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 1.3 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Riley County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Riley County's mapped high-risk flood zone (the Special Flood Hazard Area, or SFHA) are legally required to carry an NFIP flood policy. In practice, 32.4% of them do — 157 active policies against 484 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 1.5% of all residential structures in Riley County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Riley County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Riley County ranks 1319 — 1 being the highest hazard nationally — and 766 by population among all 3144 counties covered here, where 1 is the largest. About 72,557 people live in Riley County, Kansas, spread over 609.66 square miles.
What to do next if you own or are buying in Riley County
314 of Riley County's 20,716 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Riley 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.