Santa Clara County, CA: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Santa Clara County scores at the 99.8th percentile for flood hazard, rated "Very High" — among the highest flood hazard in the country. 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 2.1 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.
Santa Clara County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Santa Clara 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, 21.6% of them do — 6,986 active policies against 32,371 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 1.7% of all residential structures in Santa Clara County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
Where Santa Clara County ranks
Among the 3144 US counties FEMA scores for flood hazard, Santa Clara County ranks 9 — 1 being the highest hazard nationally — and 18 by population among all 3144 counties covered here, where 1 is the largest. About 1,926,325 people live in Santa Clara County, California, spread over 1,291.084 square miles.
Checking a specific address in Santa Clara County
Across all of Santa Clara County's 486,356 residential structures, 8,141 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Santa Clara 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.