How much flood risk does Clark County actually carry?
Clark County lands at the 5.4th percentile of FEMA's National Risk Index for flooding, "Very Low" territory — among the lowest flood hazard in the country — with the hazard 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. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Mandatory flood insurance compliance in Clark County
Clark County is one of the counties where FEMA's own denominator for mandated flood-zone structures is missing, so no compliance rate is shown rather than a guessed one — the data quality guide covers how common this is. Across all residential structures in Clark County, not just the ones FEMA mandates, 0.7% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How Clark County compares nationally
Clark County sits at rank 2982 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 2887 of 3144 by population (1 is biggest). Clark County, South Dakota covers 957.512 square miles and counts roughly 3,974 residents.
What to do next if you own or are buying in Clark County
Across all of Clark County's 1,531 residential structures, 10 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed Clark County's numbers. See the data quality guide for why Clark County, like hundreds of other counties, doesn't get a clean compliance percentage.