Valley County, Montana
Shrink-swell clay limits houses without basements on 51% of Valley County's mapped land, a higher share than 91% of US counties and the 5th highest of 53 Montana counties. A shallow water table limits basements on 2%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 7 flood losses here since 2016. 81% of homes were built before 1980, against 50% nationally; the median home dates from 1966.
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 Valley County
| Expansive clay (limits slab homes) | 50.9% |
| High water table (limits basements) | 2.4% |
| Septic fields very limited | 85.0% |
| Clay swell (LEP, by area) | 6.0% |
| High-swell land (LEP 6%+) | 50.6% |
| Mapped soil | 3,242,600 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Phillips | 12% | n/a |
| Kevin | 7% | n/a |
| Elloam | 7% | n/a |
| Sunburst | 6% | n/a |
| Lisam | 5% | n/a |
| Dilts | 4% | n/a |
How we count · survey areas MT105 (2025-08-29)
What the numbers mean here
Clay swell averages a linear extensibility of 6.0% by land area here, and 51% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 51% of the mapped land.
Rain over the 12 months to August 2026: 12.80 in, 0.96 in below the 1991-2020 average year of 13.76 in.
USDA rates 85% of the land very limited for septic absorption fields.
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 36 of the last 52 weeks; the most was 100% of its area, in 5 weeks, most recently on the March 31, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
7 flood losses since 2016, $1,621 paid. The worst year was 2019, with 7.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 7 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 13.76 in |
| 12 months to August 2026 | 12.80 in (-0.96) |
| 2025 | 12.44 in (-1.32) |
| Wettest year since 1895 | 1906: 20.76 in |
| Driest year since 1895 | 2017: 6.29 in |
| Days with 1 inch or more, normal at GLASGOW INTL AP (10 mi away) | 1.8 |
Homes
| Housing units | 4,254 |
| Median year built | 1966 |
| Built before 1980 | 81% |
| Built 2000 or later | 7% |
| Owner-occupied | 79% |
| Median value, owner-occupied | $198,400 |
| Single-family detached | 71% |
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 |
|---|---|---|---|
| Phillips County, MT | 58 mi | 64% | 2% |
| Daniels County, MT | 60 mi | 3% | 1% |
| McCone County, MT | 65 mi | 12% | under 1% |
| Garfield County, MT | 76 mi | 22% | under 1% |
| Roosevelt County, MT | 77 mi | 10% | 2% |
| Sheridan County, MT | 101 mi | 6% | 2% |
| Richland County, MT | 105 mi | 8% | 2% |
| Blaine County, MT | 106 mi | 44% | 2% |
Sources: USDA SSURGO (August 29, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status