Costilla County, CO: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Costilla County scores at the 17.2th percentile for flood hazard, rated "Very Low" — among the lowest 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 once every 2 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 Costilla County
FEMA hasn't published a residential structure count for Costilla 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 Costilla County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Costilla County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Costilla County ranks 2639 — 1 being the highest hazard nationally — and 2910 by population among all 3144 counties covered here, where 1 is the largest. About 3,686 people live in Costilla County, Colorado, spread over 1,227.593 square miles.
Your street may differ from Costilla County's average
FEMA counts 2,264 residential structures in Costilla County overall, 10 of them carrying some form of NFIP coverage — but a lender or insurer cares about one parcel, not that county total.
Where Costilla County's figures come from
Every figure on this page traces to a named FEMA dataset, documented in the methodology guide. Costilla 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.