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Coos County, New Hampshire

A shallow water table limits basements on 53% of Coos County's mapped land, a higher share than 69% of US counties and the highest of 10 New Hampshire counties. Shrink-swell clay limits houses without basements on under 1%.

The soil survey maps 82% of the county's land area; these shares describe the mapped part. 100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 17 flood losses here since 2016. 64% of homes were built before 1980, against 50% nationally; the median home dates from 1969.

Data as of October 13, 2026 · sources

<1%

expansive clay: shrink-swell limits slab homes

53%

high water table: limits basements

100%

in drought, October 13, 2026

64%

of homes built before 1980

Soil under Coos County

Expansive clay (limits slab homes)0.4%
High water table (limits basements)53.1%
Septic fields very limited92.3%
Clay swell (LEP, by area)1.1%
High-swell land (LEP 6%+)0.5%
Mapped soil937,533 acres
Soil seriesShare hereSeries nationally: high water table
Tunbridge11%n/a
Peru8%n/a
Howland7%n/a
Cabot6%n/a
Lyman5%n/a
Marlow5%n/a
Essex County: 71%Oxford County: 48%Caledonia County: 49%Franklin County: 58%Orleans County: 59%Carroll County: 36%Grafton County: 29%Androscoggin County: 45%Coos County EssexOxfordCaledoniaFranklinOrleansCarrollGraftonAndroscogginCoos
Coos 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 NH607 (2025-09-10)

What the numbers mean here

On 53% of Coos 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: 43.08 in, 4.57 in below the 1991-2020 average year of 47.65 in.

USDA rates 92% of the land very limited for septic absorption fields.

Drought

100% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 38 of the last 52 weeks; the most was 100% of its area, in 27 weeks, most recently on the October 13, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse100%
D1 moderate drought or worse100%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

17 flood losses since 2016, $185,088 paid. The worst year was 2023, with 7.

YearFlood losses
20160
20176
20181
20191
20200
20210
20221
20237
20241
20250
2026 to date0

Rain

Average year, 1991-202047.65 in
12 months to August 202643.08 in (-4.57)
202540.51 in (-7.14)
Wettest year since 18951954: 61.40 in
Driest year since 18951914: 33.34 in
Days with 1 inch or more, normal at YORK POND (10 mi away)9.4

Homes

Housing units20,637
Median year built1969
Built before 198064%
Built 2000 or later14%
Owner-occupied74%
Median value, owner-occupied$188,900
Single-family detached68%

What repairs cost

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

WorkRangeSource
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

PlaceDistanceExpansive clayHigh water table
Essex County, VT 22 mi 0% 71%
Oxford County, ME 29 mi 0% 48%
Caledonia County, VT 42 mi 0% 49%
Franklin County, ME 48 mi 0% 58%
Orleans County, VT 49 mi 0% 59%
Carroll County, NH 54 mi 2% 36%
Grafton County, NH 57 mi 1% 29%
Androscoggin County, ME 63 mi 0% 45%

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