Grand Isle County, Vermont
A shallow water table limits basements on 65% of Grand Isle County's mapped land, a higher share than 78% of US counties and the 2nd highest of 14 Vermont counties. Shrink-swell clay limits houses without basements on 21%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 2 flood losses here since 2016. 44% of homes were built before 1980, against 50% nationally; the median home dates from 1984.
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 Grand Isle County
| Expansive clay (limits slab homes) | 20.6% |
| High water table (limits basements) | 65.0% |
| Septic fields very limited | 90.5% |
| Clay swell (LEP, by area) | 3.4% |
| High-swell land (LEP 6%+) | 20.6% |
| Mapped soil | 56,700 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Covington | 21% | n/a |
| Benson | 20% | n/a |
| Amenia | 12% | n/a |
| Kendaia | 12% | n/a |
| Carlisle | 6% | n/a |
| Livingston | 4% | n/a |
How we count · survey areas VT013 (2025-09-16)
What the numbers mean here
Clay swell averages a linear extensibility of 3.4% by land area here, and 21% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 21% of the mapped land.
On 65% of Grand Isle 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: 39.49 in, 0.64 in above the 1991-2020 average year of 38.85 in.
USDA rates 91% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 3 of the last 52 weeks; the most was 100% of its area, in 3 weeks, most recently on the November 4, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
2 flood losses since 2016, $22,169 paid. The worst year was 2019, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 38.85 in |
| 12 months to August 2026 | 39.49 in (+0.64) |
| 2025 | 35.51 in (-3.34) |
| Wettest year since 1895 | 1954: 46.93 in |
| Driest year since 1895 | 1908: 25.71 in |
| Days with 1 inch or more, normal at S HERO (12 mi away) | 6.2 |
Homes
| Housing units | 5,326 |
| Median year built | 1984 |
| Built before 1980 | 44% |
| Built 2000 or later | 27% |
| Owner-occupied | 90% |
| Median value, owner-occupied | $394,100 |
| Single-family detached | 82% |
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 |
|---|---|---|---|
| Franklin County, VT | 20 mi | 1% | 52% |
| Clinton County, NY | 20 mi | 3% | 51% |
| Chittenden County, VT | 26 mi | 3% | 39% |
| Lamoille County, VT | 35 mi | 0% | 24% |
| Washington County, VT | 48 mi | 0% | 35% |
| Orleans County, VT | 51 mi | 0% | 59% |
| Franklin County, NY | 52 mi | 1% | 52% |
| Essex County, NY | 53 mi | 3% | 31% |
Sources: USDA SSURGO (September 16, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status