Merrimack County, NH: flood risk, in FEMA's own numbers
On FEMA's National Risk Index, Merrimack County scores at the 85.8th 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 2.6 times a year. This describes the county, not any one street — FEMA only publishes exact parcel zones through a live map service.
Merrimack County's flood-insurance compliance gap
Homes with a federally backed mortgage inside Merrimack 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, 20.1% of them do — 215 active policies against 1,069 structures FEMA counts in that zone, leaving a real compliance gap. Looking beyond the mandated zone, 0.8% of all residential structures in Merrimack County carry flood coverage voluntarily or otherwise — relevant because most NFIP claims nationally come from outside the mapped SFHA.
How Merrimack County compares nationally
Among the 3144 US counties FEMA scores for flood hazard, Merrimack County ranks 469 — 1 being the highest hazard nationally — and 444 by population among all 3144 counties covered here, where 1 is the largest. Merrimack County, New Hampshire is home to about 157,869 people across 932.851 square miles of land.
Checking a specific address in Merrimack County
Across all of Merrimack County's 39,725 residential structures, 333 carry an NFIP policy today — a county-wide count that still can't tell you one address's own mapped zone.
Where Merrimack 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.