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Douglas County, South Dakota
Shrink-swell clay limits houses without basements on 33% of Douglas County's mapped land, a higher share than 82% of US counties. A shallow water table limits basements on 21%.
87.7% 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. 73% of homes were built before 1980, against 50% nationally; the median home dates from 1960.
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 Douglas County
| Expansive clay (limits slab homes) | 32.7% |
| High water table (limits basements) | 20.9% |
| Septic fields very limited | 96.1% |
| Clay swell (LEP, by area) | 5.3% |
| High-swell land (LEP 6%+) | 32.9% |
| Mapped soil | 277,741 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Eakin | 14% | n/a |
| Highmore | 13% | n/a |
| Ethan | 11% | n/a |
| Clarno | 11% | 0% |
| Tetonka | 10% | n/a |
| Walke | 5% | n/a |
How we count · survey areas SD043 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 5.3% by land area here, and 33% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 33% of the mapped land.
Clay shrinks as it dries: 87.7% of the county is in drought on the latest map, and 33% of Douglas County's mapped land has shrink-swell clay.
On 21% of Douglas 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: 18.15 in, 7.13 in below the 1991-2020 average year of 25.28 in.
USDA rates 96% of the land very limited for septic absorption fields.
Drought
87.7% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 50 of the last 52 weeks; the most was 100% of its area, in 30 weeks, most recently on the September 15, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 87.7% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Douglas County since 2016.
Rain
| Average year, 1991-2020 | 25.28 in |
| 12 months to August 2026 | 18.15 in (-7.13) |
| 2025 | 24.77 in (-0.51) |
| Wettest year since 1895 | 2019: 40.91 in |
| Driest year since 1895 | 1974: 14.34 in |
| Days with 1 inch or more, normal at PLATTE (24 mi away) | 5.1 |
Homes
| Housing units | 1,338 |
| Median year built | 1960 |
| Built before 1980 | 73% |
| Built 2000 or later | 18% |
| Owner-occupied | 77% |
| Median value, owner-occupied | $166,900 |
| Single-family detached | 90% |
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 |
|---|---|---|---|
| Charles Mix County, SD | 17 mi | 29% | 13% |
| Davison County, SD | 22 mi | 18% | 20% |
| Aurora County, SD | 25 mi | 42% | 19% |
| Hutchinson County, SD | 31 mi | 21% | 25% |
| Hanson County, SD | 34 mi | 21% | 25% |
| Bon Homme County, SD | 37 mi | 27% | 26% |
| Boyd County, NE | 40 mi | 52% | 13% |
| Brule County, SD | 44 mi | 43% | 12% |
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