Lewis County, NY flood risk explained
Flood hazard in Lewis County sits at the 49.9th national percentile, below 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 1 times a year. That's a county-wide figure, not a per-address one — FEMA's parcel maps are a live lookup, not a bulk file.
Lewis County's flood-insurance compliance gap
FEMA hasn't published a residential structure count for Lewis County's mapped flood zone, so a reliable mandatory-compliance percentage can't be computed here — see the data quality guide for why this gap exists for roughly a quarter of US counties. Looking beyond the mandated zone, 0.4% of all residential structures in Lewis County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Lewis County ranks
Among the 3144 US counties FEMA scores for flood hazard, Lewis County ranks 1636 — 1 being the highest hazard nationally — and 1554 by population among all 3144 counties covered here, where 1 is the largest. Lewis County, New York is home to about 26,570 people across 1,276.309 square miles of land.
Your street may differ from Lewis County's average
Across all of Lewis County's 14,255 residential structures, 59 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Lewis County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. Lewis County's compliance figure is one of the ones affected by FEMA's incomplete denominator data — the data quality guide explains what that means and how many counties it touches.