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Marshall County, South Dakota
A shallow water table limits basements on 57% of Marshall County's mapped land, a higher share than 72% of US counties and the 8th highest of 66 South Dakota counties. Shrink-swell clay limits houses without basements on 22%.
71.8% 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. 68% of homes were built before 1980, against 50% nationally; the median home dates from 1970.
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 Marshall County
| Expansive clay (limits slab homes) | 21.7% |
| High water table (limits basements) | 57.2% |
| Septic fields very limited | 84.7% |
| Clay swell (LEP, by area) | 4.6% |
| High-swell land (LEP 6%+) | 22.8% |
| Mapped soil | 566,854 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Forman | 18% | n/a |
| Aastad | 7% | n/a |
| Beotia | 7% | n/a |
| Buse | 6% | n/a |
| Southam | 4% | n/a |
| Bearden | 3% | n/a |
How we count · survey areas SD091 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 4.6% by land area here, and 23% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 22% of the mapped land.
Clay shrinks as it dries: 71.8% of the county is in drought on the latest map, and 22% of Marshall County's mapped land has shrink-swell clay.
On 57% of Marshall 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: 20.38 in, 3.77 in below the 1991-2020 average year of 24.15 in.
USDA rates 85% of the land very limited for septic absorption fields.
Drought
71.8% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 7 of the last 52 weeks; the most was 71.8% of its area, in 3 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 | 71.8% |
| D2 severe or worse | 1.8% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Marshall County since 2016.
Rain
| Average year, 1991-2020 | 24.15 in |
| 12 months to August 2026 | 20.38 in (-3.77) |
| 2025 | 27.18 in (+3.03) |
| Wettest year since 1895 | 1916: 34.71 in |
| Driest year since 1895 | 1976: 9.13 in |
| Days with 1 inch or more, normal at BRITTON (9 mi away) | 5.4 |
Homes
| Housing units | 2,436 |
| Median year built | 1970 |
| Built before 1980 | 68% |
| Built 2000 or later | 20% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $156,500 |
| Single-family detached | 83% |
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 |
|---|---|---|---|
| Sargent County, ND | 26 mi | 16% | 71% |
| Day County, SD | 26 mi | 19% | 63% |
| Roberts County, SD | 32 mi | 26% | 60% |
| Brown County, SD | 39 mi | 28% | 56% |
| Richland County, ND | 48 mi | 29% | 90% |
| Ransom County, ND | 49 mi | 12% | 62% |
| Dickey County, ND | 51 mi | 20% | 60% |
| Traverse County, MN | 53 mi | 21% | 94% |
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