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Carroll County, New Hampshire
A shallow water table limits basements on 36% of Carroll County's mapped land, a higher share than 55% of US counties and the 6th highest of 10 New Hampshire counties. Shrink-swell clay limits houses without basements on 2%.
The soil survey maps 81% 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 47 flood losses here since 2016, 51% of them in buildings with basements. 46% of homes were built before 1980, against 50% nationally; the median home dates from 1982.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Carroll County
| Expansive clay (limits slab homes) | 1.8% |
| High water table (limits basements) | 36.5% |
| Septic fields very limited | 82.7% |
| Clay swell (LEP, by area) | 1.2% |
| High-swell land (LEP 6%+) | 1.8% |
| Mapped soil | 480,061 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Berkshire | 9% | n/a |
| Becket | 7% | n/a |
| Lyman | 6% | n/a |
| Marlow | 5% | n/a |
| Henniker | 5% | n/a |
| Monadnock | 5% | n/a |
How we count · survey areas NH603 (2025-09-10)
What the numbers mean here
On 36% of Carroll 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: 43.93 in, 7.74 in below the 1991-2020 average year of 51.67 in.
USDA rates 83% 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 52 of the last 52 weeks; the most was 100% of its area, in 32 weeks, most recently on the October 13, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 100% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
47 flood losses since 2016, $980,903 paid. The worst year was 2023, with 26. Foundations of the buildings, where recorded: 51% basements, 17% slabs, 14% crawl spaces, 17% elevated. Median water depth outside the building: 30 in.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 14 |
| 2018 | 1 |
| 2019 | 4 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 26 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 51.67 in |
| 12 months to August 2026 | 43.93 in (-7.74) |
| 2025 | 40.86 in (-10.81) |
| Wettest year since 1895 | 2005: 67.39 in |
| Driest year since 1895 | 1941: 34.21 in |
| Days with 1 inch or more, normal at N CONWAY (13 mi away) | 13.7 |
Homes
| Housing units | 40,421 |
| Median year built | 1982 |
| Built before 1980 | 46% |
| Built 2000 or later | 20% |
| Owner-occupied | 83% |
| Median value, owner-occupied | $388,900 |
| Single-family detached | 77% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Belknap County, NH | 27 mi | 2% | 42% |
| Grafton County, NH | 32 mi | 1% | 29% |
| York County, ME | 40 mi | 3% | 52% |
| Strafford County, NH | 41 mi | 1% | 39% |
| Cumberland County, ME | 44 mi | 0% | 49% |
| Merrimack County, NH | 46 mi | 2% | 49% |
| Oxford County, ME | 49 mi | 0% | 48% |
| Androscoggin County, ME | 54 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