Brown County, SD: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Brown County scores at the 63.1th 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 5.2 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Who actually carries the flood insurance FEMA requires
8.1% of the homes FEMA requires to carry flood insurance in Brown County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 72 policies against 884 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.7% of all residential structures in Brown County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Brown County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Brown County ranks 1212 — 1 being the highest hazard nationally — and 1252 by population among all 3144 counties covered here, where 1 is the largest. Brown County, South Dakota is home to about 37,495 people across 1,713.03 square miles of land.
Checking a specific address in Brown County
114 of Brown County's 17,129 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where Brown 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.