Grant County, Wisconsin
Shrink-swell clay limits houses without basements on 23% of Grant County's mapped land, a higher share than 74% of US counties and the 10th highest of 72 Wisconsin counties. A shallow water table limits basements on 11%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 21 flood losses here since 2016. 61% of homes were built before 1980, against 50% nationally; the median home dates from 1973.
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 Grant County
| Expansive clay (limits slab homes) | 23.4% |
| High water table (limits basements) | 11.0% |
| Septic fields very limited | 93.6% |
| Clay swell (LEP, by area) | 5.0% |
| High-swell land (LEP 6%+) | 35.8% |
| Mapped soil | 755,980 acres |
How we count · survey areas WI043 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 5.0% by land area here, and 36% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 23% of the mapped land.
Rain over the 12 months to August 2026: 36.97 in, 0.97 in below the 1991-2020 average year of 37.94 in.
USDA rates 94% 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 13 of the last 52 weeks; the most was 32.5% of its area, in 2 weeks, most recently on the March 3, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
21 flood losses since 2016, $335,936 paid. The worst year was 2023, with 5.
| Year | Flood losses |
|---|---|
| 2016 | 2 |
| 2017 | 5 |
| 2018 | 1 |
| 2019 | 5 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 5 |
| 2024 | 0 |
| 2025 | 2 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 37.94 in |
| 12 months to August 2026 | 36.97 in (-0.97) |
| 2025 | 34.09 in (-3.85) |
| Wettest year since 1895 | 2019: 52.96 in |
| Driest year since 1895 | 1988: 20.79 in |
| Days with 1 inch or more, normal at LANCASTER 4 WSW (6 mi away) | 9.4 |
Homes
| Housing units | 22,332 |
| Median year built | 1973 |
| Built before 1980 | 61% |
| Built 2000 or later | 19% |
| Owner-occupied | 70% |
| Median value, owner-occupied | $200,700 |
| Single-family detached | 75% |
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 |
|---|---|---|---|
| Crawford County, WI | 28 mi | 5% | 9% |
| Dubuque County, IA | 30 mi | 9% | 25% |
| Iowa County, WI | 30 mi | 37% | 12% |
| Clayton County, IA | 32 mi | 1% | 14% |
| Lafayette County, WI | 32 mi | 29% | 14% |
| Richland County, WI | 37 mi | 7% | 15% |
| Jo Daviess County, IL | 43 mi | 17% | 20% |
| Delaware County, IA | 44 mi | 4% | 53% |
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