Thurston County, WA: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Thurston County scores at the 90.8th percentile for flood hazard, rated "Relatively Moderate" — a middling flood hazard by national standards. 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 7 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 Thurston County
42.8% of the homes FEMA requires to carry flood insurance in Thurston County — those inside the mapped Special Flood Hazard Area — actually have a policy in force: 406 policies against 948 mandated structures, which means a meaningful share of legally-required coverage simply isn't there. Looking beyond the mandated zone, 0.9% of all residential structures in Thurston County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Thurston County against the rest of the country
Among the 3144 US counties FEMA scores for flood hazard, Thurston County ranks 308 — 1 being the highest hazard nationally — and 243 by population among all 3144 counties covered here, where 1 is the largest. About 302,912 people live in Thurston County, Washington, spread over 722.513 square miles.
Your street may differ from Thurston County's average
FEMA counts 77,037 residential structures in Thurston County overall, 703 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where Thurston 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.