Roosevelt County, Montana
USDA's soil survey flags shrink-swell clay on 10% of Roosevelt County's mapped land and a shallow water table under basements on 2%, both below the national shares of 15% and 29%. 1.4% 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. 58% of homes were built before 1980, against 50% nationally; the median home dates from 1974.
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 Roosevelt County
| Expansive clay (limits slab homes) | 9.6% |
| High water table (limits basements) | 2.1% |
| Septic fields very limited | 85.5% |
| Clay swell (LEP, by area) | 4.2% |
| High-swell land (LEP 6%+) | 9.6% |
| Mapped soil | 1,517,400 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Zahill | 22% | n/a |
| Vida | 14% | n/a |
| Williams | 8% | 0% |
| Dooley | 5% | n/a |
| Turner | 4% | n/a |
| Farnuf | 4% | n/a |
How we count · survey areas MT661 (2025-09-03)
What the numbers mean here
Rain over the 12 months to August 2026: 10.82 in, 3.20 in below the 1991-2020 average year of 14.02 in.
USDA rates 85% of the land very limited for septic absorption fields.
With shrink-swell clay on 10% and a shallow water table on 2% of the land, the soil survey points to neither problem across most of Roosevelt County; conditions still vary lot by lot.
Drought
1.4% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 45 of the last 52 weeks; the most was 100% of its area, in 5 weeks, most recently on the June 23, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 26.4% |
| D1 moderate drought or worse | 1.4% |
| 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 Roosevelt County since 2016.
Rain
| Average year, 1991-2020 | 14.02 in |
| 12 months to August 2026 | 10.82 in (-3.20) |
| 2025 | 13.62 in (-0.40) |
| Wettest year since 1895 | 1906: 22.39 in |
| Driest year since 1895 | 1934: 5.76 in |
| Days with 1 inch or more, normal at BREDETTE (21 mi away) | 1.8 |
Homes
| Housing units | 4,066 |
| Median year built | 1974 |
| Built before 1980 | 58% |
| Built 2000 or later | 16% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $118,800 |
| Single-family detached | 77% |
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 |
|---|---|---|---|
| Sheridan County, MT | 36 mi | 6% | 2% |
| Richland County, MT | 40 mi | 8% | 2% |
| Daniels County, MT | 43 mi | 3% | 1% |
| McCone County, MT | 57 mi | 12% | under 1% |
| Williams County, ND | 69 mi | 8% | 9% |
| Dawson County, MT | 70 mi | 8% | 1% |
| Valley County, MT | 77 mi | 51% | 2% |
| Divide County, ND | 77 mi | 21% | 23% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status