HomeSouth DakotaMinnehaha County
Minnehaha County, South Dakota
A shallow water table limits basements on 32% of Minnehaha County's mapped land, a higher share than 51% of US counties. Shrink-swell clay limits houses without basements on 17%.
96% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 124 flood losses here since 2016, 57% of them in buildings with basements. 42% of homes were built before 1980, against 50% nationally; the median home dates from 1987.
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 Minnehaha County
| Expansive clay (limits slab homes) | 17.3% |
| High water table (limits basements) | 31.9% |
| Septic fields very limited | 75.8% |
| Clay swell (LEP, by area) | 4.6% |
| High-swell land (LEP 6%+) | 14.6% |
| Mapped soil | 520,627 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Nora | 12% | n/a |
| Moody | 10% | 0% |
| Egan | 8% | n/a |
| Trent | 8% | n/a |
| Crofton | 6% | n/a |
| Ethan | 6% | n/a |
How we count · survey areas SD099 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 4.6% by land area here, and 15% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 17% of the mapped land.
Clay shrinks as it dries: 96% of the county is in drought on the latest map, and 17% of Minnehaha County's mapped land has shrink-swell clay.
On 32% of Minnehaha 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: 17.96 in, 9.67 in below the 1991-2020 average year of 27.63 in.
USDA rates 76% of the land very limited for septic absorption fields.
Drought
96% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 30 weeks, most recently on the September 29, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 96% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
124 flood losses since 2016, $3.9 million paid. The worst year was 2019, with 93. Foundations of the buildings, where recorded: 57% basements, 32% slabs, 4% crawl spaces, 7% elevated. Median water depth outside the building: 14 in.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 2 |
| 2018 | 5 |
| 2019 | 93 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 22 |
| 2025 | 1 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 27.63 in |
| 12 months to August 2026 | 17.96 in (-9.67) |
| 2025 | 23.41 in (-4.22) |
| Wettest year since 1895 | 2019: 40.47 in |
| Driest year since 1895 | 1976: 12.15 in |
| Days with 1 inch or more, normal at SIOUX FALLS (6 mi away) | 6 |
Homes
| Housing units | 89,418 |
| Median year built | 1987 |
| Built before 1980 | 42% |
| Built 2000 or later | 33% |
| Owner-occupied | 63% |
| Median value, owner-occupied | $287,600 |
| Single-family detached | 59% |
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 |
|---|---|---|---|
| Moody County, SD | 25 mi | 10% | 36% |
| Rock County, MN | 27 mi | 24% | 54% |
| Lincoln County, SD | 27 mi | 28% | 51% |
| McCook County, SD | 28 mi | 26% | 33% |
| Lake County, SD | 30 mi | 30% | 27% |
| Turner County, SD | 31 mi | 20% | 39% |
| Lyon County, IA | 35 mi | 18% | 37% |
| Pipestone County, MN | 36 mi | 8% | 75% |
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