Is Marathon County, WI in a flood zone?
FEMA's National Risk Index puts Marathon County's flood hazard at the 87.7th percentile nationally — 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 once every 1 years. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Mandatory flood insurance compliance in Marathon County
18.8% of the homes FEMA requires to carry flood insurance in Marathon County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 141 policies against 750 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Across all residential structures in Marathon County, not just the ones FEMA mandates, 0.4% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Where Marathon County ranks
Marathon County sits at rank 407 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 481 of 3144 by population (1 is biggest). About 139,091 people live in Marathon County, Wisconsin, spread over 1,545.249 square miles.
Checking a specific address in Marathon County
Across all of Marathon County's 45,332 residential structures, 199 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 Marathon County's numbers. The guide to what the Special Flood Hazard Area actually means explains why the mandatory-insurance rule exists and who it applies to.