St. Croix County, WI: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, St. Croix County scores at the 64.1th 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 once every 2 years. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Who actually carries the flood insurance FEMA requires
Homes with a federally backed mortgage inside St. Croix County's mapped high-risk flood zone (the Special Flood Hazard Area, or SFHA) are legally required to carry an NFIP flood policy. In practice, 17.3% of them do — 64 active policies against 370 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 0.4% of all residential structures in St. Croix County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where St. Croix County ranks
Among the 3144 US counties FEMA scores for flood hazard, St. Croix County ranks 1178 — 1 being the highest hazard nationally — and 632 by population among all 3144 counties covered here, where 1 is the largest. St. Croix County, Wisconsin is home to about 97,954 people across 722.158 square miles of land.
What to do next if you own or are buying in St. Croix County
95 of St. Croix County's 25,574 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
Where St. Croix 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.