Belknap County, New Hampshire

A shallow water table limits basements on 42% of Belknap County's mapped land, a higher share than 60% of US counties and the 4th highest of 10 New Hampshire counties. Shrink-swell clay limits houses without basements on 2%.

81% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 52% of homes were built before 1980, against 50% nationally; the median home dates from 1979.

Data as of October 13, 2026 · sources

expansive clay: shrink-swell limits slab homes

42%

high water table: limits basements

81%

in drought, October 13, 2026

52%

of homes built before 1980

Soil under Belknap County

Expansive clay (limits slab homes)	1.9%
High water table (limits basements)	41.9%
Septic fields very limited	79.1%
Clay swell (LEP, by area)	1.5%
High-swell land (LEP 6%+)	5.1%
Mapped soil	301,491 acres

Soil series	Share here	Series nationally: high water table
Becket	8%	n/a
Tunbridge	8%	n/a
Lyman	6%	n/a
Skerry	5%	n/a
Millsite	4%	n/a
Henniker	4%	n/a

Belknap County (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas NH609 (2025-09-10)

What the numbers mean here

On 42% of Belknap County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.

Rain over the 12 months to August 2026: 39.13 in, 8.31 in below the 1991-2020 average year of 47.44 in.

USDA rates 79% of the land very limited for septic absorption fields.

Drought

81% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 32 weeks, most recently on the September 15, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026

Category, October 13, 2026	Share of county
D0 abnormally dry or worse	100%
D1 moderate drought or worse	81%
D2 severe or worse	0%
D3 extreme or worse	0%
D4 exceptional	0%

Flood losses since 2016

FEMA's flood data list no flood losses in Belknap County since 2016.

Rain

Average year, 1991-2020	47.44 in
12 months to August 2026	39.13 in (-8.31)
2025	39.86 in (-7.58)
Wettest year since 1895	2008: 63.35 in
Driest year since 1895	1965: 29.30 in
Days with 1 inch or more, normal at LAKEPORT 2 (3 mi away)	10

Homes

Housing units	39,003
Median year built	1979
Built before 1980	52%
Built 2000 or later	22%
Owner-occupied	80%
Median value, owner-occupied	$374,900
Single-family detached	74%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

Work	Range	Source
Basement waterproofing, US	$3,000 to $10,000	Fixr, February 6, 2026
Sump pump installation, US	$800 to $2,000	Fixr, January 31, 2025
Crawl space encapsulation, US	$2,000 to $8,000	Fixr, August 29, 2025

Nearby counties

Place	Distance	Expansive clay	High water table
Merrimack County, NH	20 mi	2%	49%
Strafford County, NH	25 mi	1%	39%
Carroll County, NH	27 mi	2%	36%
Grafton County, NH	35 mi	1%	29%
York County, ME	38 mi	3%	52%
Rockingham County, NH	40 mi	under 1%	48%
Sullivan County, NH	41 mi	2%	26%
Hillsborough County, NH	45 mi	3%	28%

Sources: USDA SSURGO (September 10, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status