HomeNorth DakotaSlope County
Slope County, North Dakota
Shrink-swell clay limits houses without basements on 23% of Slope County's mapped land, a higher share than 73% of US counties. A shallow water table limits basements on 6%.
100% 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. 66% of homes were built before 1980, against 50% nationally; the median home dates from 1961.
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 Slope County
| Expansive clay (limits slab homes) | 22.7% |
| High water table (limits basements) | 5.7% |
| Septic fields very limited | 75.4% |
| Clay swell (LEP, by area) | 3.6% |
| High-swell land (LEP 6%+) | 23.9% |
| Mapped soil | 781,300 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Patent | 5% | n/a |
| Sen | 5% | n/a |
| Cabbart | 5% | under 1% |
| Cabba | 4% | n/a |
| Daglum | 4% | n/a |
| Chama | 4% | n/a |
How we count · survey areas ND087 (2026-05-04)
What the numbers mean here
Clay swell averages a linear extensibility of 3.6% by land area here, and 24% 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.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 23% of Slope County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 14.29 in, 1.36 in below the 1991-2020 average year of 15.65 in.
USDA rates 75% of the land very limited for septic absorption fields.
Drought
100% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 18 of the last 52 weeks; the most was 100% of its area, in 12 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 | 100% |
| D2 severe or worse | 94.7% |
| D3 extreme or worse | 34.8% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Slope County since 2016.
Rain
| Average year, 1991-2020 | 15.65 in |
| 12 months to August 2026 | 14.29 in (-1.36) |
| 2025 | 19.44 in (+3.79) |
| Wettest year since 1895 | 2013: 25.74 in |
| Driest year since 1895 | 1936: 7.16 in |
| Days with 1 inch or more, normal at BOWMAN (18 mi away) | 2 |
Homes
| Housing units | 456 |
| Median year built | 1961 |
| Built before 1980 | 66% |
| Built 2000 or later | 14% |
| Owner-occupied | 81% |
| Median value, owner-occupied | $170,000 |
| Single-family detached | 88% |
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 |
|---|---|---|---|
| Bowman County, ND | 23 mi | 32% | 4% |
| Golden Valley County, ND | 39 mi | 7% | 3% |
| Billings County, ND | 39 mi | 25% | 4% |
| Stark County, ND | 46 mi | 37% | 4% |
| Fallon County, MT | 46 mi | 21% | 1% |
| Hettinger County, ND | 48 mi | 43% | 7% |
| Adams County, ND | 51 mi | 33% | 7% |
| Wibaux County, MT | 53 mi | 22% | 2% |
Sources: USDA SSURGO (May 4, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status