Fall River County, SD: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Fall River County scores at the 41.5th 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 once every 1 years. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Mandatory flood insurance compliance in Fall River County
Out of 148 homes FEMA counts inside Fall River County's mapped flood zone, 7 carry the flood policy federal law requires there — 4.7% compliance, short of full coverage. Looking beyond the mandated zone, 0.2% of all residential structures in Fall River County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Fall River County ranks
Among the 3144 US counties FEMA scores for flood hazard, Fall River County ranks 1901 — 1 being the highest hazard nationally — and 2632 by population among all 3144 counties covered here, where 1 is the largest. Fall River County, South Dakota covers 1,739.889 square miles and counts roughly 7,359 residents.
What to do next if you own or are buying in Fall River County
Across all of Fall River County's 4,954 residential structures, 8 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Fall River 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.