How much flood risk does St. Lawrence County actually carry?
St. Lawrence County lands at the 85th percentile of FEMA's National Risk Index for flooding, "Relatively Moderate" territory — a middling flood hazard by national standards — 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.
St. Lawrence County's flood-insurance compliance gap
St. Lawrence 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 St. Lawrence County, not just the ones FEMA mandates, 0.3% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
How St. Lawrence County compares nationally
St. Lawrence County sits at rank 494 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 592 of 3144 by population (1 is biggest). About 106,198 people live in St. Lawrence County, New York, spread over 2,679.534 square miles.
Checking a specific address in St. Lawrence County
109 of St. Lawrence County's 43,533 residential structures carry flood coverage of some kind, per FEMA's latest count — useful context, not a substitute for checking one parcel.
More on how this number was built
The methodology guide shows exactly which FEMA and Census tables feed St. Lawrence County's numbers. See the data quality guide for why St. Lawrence County, like hundreds of other counties, doesn't get a clean compliance percentage.