Beaverhead County, Montana
USDA's soil survey flags shrink-swell clay on 6% of Beaverhead County's mapped land and a shallow water table under basements on 9%, both below the national shares of 15% and 29%. None of the county is in drought on the October 13, 2026 Drought Monitor map, after 4.8% a week earlier.
FEMA's flood data list no flood losses here since 2016. 52% of homes were built before 1980, against 50% nationally; the median home dates from 1979.
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 Beaverhead County
| Expansive clay (limits slab homes) | 6.1% |
| High water table (limits basements) | 9.1% |
| Septic fields very limited | 77.3% |
| Clay swell (LEP, by area) | 3.0% |
| High-swell land (LEP 6%+) | 7.1% |
| Mapped soil | 3,569,418 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Philipsburg | 3% | n/a |
| Bronec | 2% | n/a |
| Maciver | 2% | n/a |
| Libeg | 2% | n/a |
| Kalsted | 2% | n/a |
| Tibson | 1% | n/a |
How we count · survey areas MT604 (2025-08-30), MT605 (2025-08-29), MT610 (2025-08-30), MT612 (2025-08-30), MT614 (2025-08-30), MT670 (2025-09-03)
What the numbers mean here
Rain over the 12 months to August 2026: 19.76 in, 0.46 in below the 1991-2020 average year of 20.22 in.
USDA rates 77% of the land very limited for septic absorption fields.
With shrink-swell clay on 6% and a shallow water table on 9% of the land, the soil survey points to neither problem across most of Beaverhead County; conditions still vary lot by lot.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 51 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 | 14.2% |
| D1 moderate drought or worse | 0% |
| 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 Beaverhead County since 2016.
Rain
| Average year, 1991-2020 | 20.22 in |
| 12 months to August 2026 | 19.76 in (-0.46) |
| 2025 | 19.75 in (-0.47) |
| Wettest year since 1895 | 1909: 29.64 in |
| Driest year since 1895 | 1966: 14.02 in |
| Days with 1 inch or more, normal at GRANT 5 SE (13 mi away) | 0.2 |
Homes
| Housing units | 4,981 |
| Median year built | 1979 |
| Built before 1980 | 52% |
| Built 2000 or later | 21% |
| Owner-occupied | 66% |
| Median value, owner-occupied | $308,300 |
| Single-family detached | 70% |
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 |
|---|---|---|---|
| Madison County, MT | 49 mi | 3% | 4% |
| Lemhi County, ID | 51 mi | 10% | 12% |
| Silver Bow County, MT | 54 mi | 2% | 5% |
| Clark County, ID | 64 mi | 4% | 4% |
| Deer Lodge County, MT | 67 mi | 6% | 10% |
| Jefferson County, MT | 79 mi | 1% | 7% |
| Ravalli County, MT | 88 mi | under 1% | 8% |
| Gallatin County, MT | 88 mi | 9% | 9% |
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