Waukesha County, WI flood risk explained
Flood hazard in Waukesha County sits at the 89.8th national percentile, a middling flood hazard by national standards; driven by inland rivers and flash flooding rather than the coast — FEMA's model puts a flood event here at about 1.8 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Mandatory flood insurance compliance in Waukesha County
66.5% of the homes FEMA requires to carry flood insurance in Waukesha County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 212 policies against 319 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.6% of all residential structures in Waukesha County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Waukesha County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Waukesha County ranks 338 — 1 being the highest hazard nationally — and 182 by population among all 3144 counties covered here, where 1 is the largest. Waukesha County, Wisconsin covers 549.727 square miles and counts roughly 417,029 residents.
What to do next if you own or are buying in Waukesha County
Across all of Waukesha County's 107,803 residential structures, 594 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Waukesha 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.