Johnson County, KS flood risk explained
Flood hazard in Johnson County sits at the 94.9th national percentile, well above the national norm for flood hazard; driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 2.5 times a year. County-wide, not parcel-specific: FEMA's real flood-zone map is queried live, never shipped as a download.
Mandatory flood insurance compliance in Johnson County
25.1% of the homes FEMA requires to carry flood insurance in Johnson County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 201 policies against 800 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.3% of all residential structures in Johnson County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Johnson County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Johnson County ranks 172 — 1 being the highest hazard nationally — and 113 by population among all 3144 counties covered here, where 1 is the largest. Johnson County, Kansas is home to about 632,276 people across 473.629 square miles of land.
Your street may differ from Johnson County's average
Across all of Johnson County's 195,981 residential structures, 544 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Johnson 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.