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Stanley County, South Dakota
Shrink-swell clay limits houses without basements on 89% of Stanley County's mapped land, a higher share than 100% of US counties and the 3rd highest of 66 South Dakota counties. A shallow water table limits basements on 6%.
41.2% 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. 37% of homes were built before 1980, against 50% nationally; the median home dates from 1993.
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 Stanley County
| Expansive clay (limits slab homes) | 88.9% |
| High water table (limits basements) | 5.7% |
| Septic fields very limited | 89.9% |
| Clay swell (LEP, by area) | 11.6% |
| High-swell land (LEP 6%+) | 88.4% |
| Mapped soil | 980,128 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Sansarc | 21% | n/a |
| Promise | 17% | n/a |
| Opal | 16% | n/a |
| Bullcreek | 7% | n/a |
| Dupree | 5% | n/a |
| Chantier | 5% | n/a |
How we count · survey areas SD117 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 11.6% by land area here, and 88% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 89% of the mapped land.
Clay shrinks as it dries: 41.2% of the county is in drought on the latest map, and 89% of Stanley County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 18.42 in, 0.58 in below the 1991-2020 average year of 19.00 in.
USDA rates 90% of the land very limited for septic absorption fields.
Drought
41.2% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 27 of the last 52 weeks; the most was 69.2% of its area, in 3 weeks, most recently on the June 2, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 65.8% |
| D1 moderate drought or worse | 41.2% |
| D2 severe or worse | 6.5% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Stanley County since 2016.
Rain
| Average year, 1991-2020 | 19.00 in |
| 12 months to August 2026 | 18.42 in (-0.58) |
| 2025 | 22.54 in (+3.54) |
| Wettest year since 1895 | 2019: 28.59 in |
| Driest year since 1895 | 1976: 7.55 in |
| Days with 1 inch or more, normal at PIERRE RGNL AP (23 mi away) | 3.6 |
Homes
| Housing units | 1,542 |
| Median year built | 1993 |
| Built before 1980 | 37% |
| Built 2000 or later | 31% |
| Owner-occupied | 83% |
| Median value, owner-occupied | $203,500 |
| Single-family detached | 67% |
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 |
|---|---|---|---|
| Jones County, SD | 32 mi | 94% | 7% |
| Sully County, SD | 37 mi | 23% | 9% |
| Hughes County, SD | 38 mi | 34% | 8% |
| Haakon County, SD | 40 mi | 89% | 6% |
| Dewey County, SD | 51 mi | 70% | 4% |
| Lyman County, SD | 57 mi | 89% | 8% |
| Mellette County, SD | 58 mi | 61% | 3% |
| Potter County, SD | 59 mi | 25% | 11% |
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