Is Lewis County, WA in a flood zone?
FEMA's National Risk Index puts Lewis County's flood hazard at the 90.9th 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 4 years. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Mandatory flood insurance compliance in Lewis County
Lewis 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 Lewis County, not just the ones FEMA mandates, 2.9% carry an NFIP policy — most flood damage nationally happens outside the mapped high-risk zone, so that broader number matters too.
Lewis County against the rest of the country
Lewis County sits at rank 306 of 3144 counties on FEMA's flood hazard scale (1 is worst) and rank 681 of 3144 by population (1 is biggest). Lewis County, Washington is home to about 87,049 people across 2,402.782 square miles of land.
Your street may differ from Lewis County's average
Across all of Lewis County's 35,507 residential structures, 1,035 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 Lewis County's numbers. See the data quality guide for why Lewis County, like hundreds of other counties, doesn't get a clean compliance percentage.