McCone County, Montana
USDA's soil survey flags shrink-swell clay on 12% of McCone County's mapped land and a shallow water table under basements on under 1%, both below the national shares of 15% and 29%. 0.7% 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. 71% of homes were built before 1980, against 50% nationally; the median home dates from 1964.
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 McCone County
| Expansive clay (limits slab homes) | 12.2% |
| High water table (limits basements) | 0.4% |
| Septic fields very limited | 73.2% |
| Clay swell (LEP, by area) | 4.2% |
| High-swell land (LEP 6%+) | 11.7% |
| Mapped soil | 1,711,722 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Cambert | 10% | n/a |
| Zahill | 6% | n/a |
| Cabba | 5% | n/a |
| Cabbart | 4% | under 1% |
| Bryant | 4% | n/a |
| Vida | 4% | n/a |
How we count · survey areas MT055 (2025-08-30)
What the numbers mean here
Rain over the 12 months to August 2026: 10.75 in, 2.84 in below the 1991-2020 average year of 13.59 in.
USDA rates 73% of the land very limited for septic absorption fields.
With shrink-swell clay on 12% and a shallow water table on under 1% of the land, the soil survey points to neither problem across most of McCone County; conditions still vary lot by lot.
Drought
0.7% 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 9 weeks, most recently on the June 23, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 14.6% |
| D1 moderate drought or worse | 0.7% |
| 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 McCone County since 2016.
Rain
| Average year, 1991-2020 | 13.59 in |
| 12 months to August 2026 | 10.75 in (-2.84) |
| 2025 | 14.17 in (+0.58) |
| Wettest year since 1895 | 1978: 20.66 in |
| Driest year since 1895 | 2017: 6.00 in |
| Days with 1 inch or more, normal at CIRCLE (17 mi away) | 1.8 |
Homes
| Housing units | 1,082 |
| Median year built | 1964 |
| Built before 1980 | 71% |
| Built 2000 or later | 14% |
| Owner-occupied | 90% |
| Median value, owner-occupied | $211,600 |
| Single-family detached | 82% |
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 |
|---|---|---|---|
| Dawson County, MT | 47 mi | 8% | 1% |
| Richland County, MT | 57 mi | 8% | 2% |
| Roosevelt County, MT | 57 mi | 10% | 2% |
| Prairie County, MT | 58 mi | 10% | 1% |
| Garfield County, MT | 63 mi | 22% | under 1% |
| Valley County, MT | 65 mi | 51% | 2% |
| Daniels County, MT | 81 mi | 3% | 1% |
| Wibaux County, MT | 83 mi | 22% | 2% |
Sources: USDA SSURGO (August 30, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status