Carbon County, Wyoming
USDA's soil survey flags shrink-swell clay on 9% of Carbon County's mapped land and a shallow water table under basements on 5%, both below the national shares of 15% and 29%. The soil survey maps 59% of the county's land area; these shares describe the mapped part.
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. 67% of homes were built before 1980, against 50% nationally; the median home dates from 1973.
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 Carbon County
| Expansive clay (limits slab homes) | 9.3% |
| High water table (limits basements) | 5.0% |
| Septic fields very limited | 60.0% |
| Clay swell (LEP, by area) | 3.2% |
| High-swell land (LEP 6%+) | 9.9% |
| Mapped soil | 2,994,498 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Rock River | 3% | n/a |
| Seminoe | 3% | n/a |
| McFadden | 3% | n/a |
| Blackhall | 2% | n/a |
| Rabbitears | 2% | n/a |
| Rawlins | 2% | n/a |
How we count · survey areas WY630 (2025-09-04)
What the numbers mean here
Rain over the 12 months to August 2026: 13.76 in, 1.79 in below the 1991-2020 average year of 15.55 in.
USDA rates 60% of the land very limited for septic absorption fields.
With shrink-swell clay on 9% and a shallow water table on 5% of the land, the soil survey points to neither problem across most of Carbon County; conditions still vary lot by lot.
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 52 of the last 52 weeks; the most was 100% of its area, in 35 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 | 71% |
| D3 extreme or worse | 7.1% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Carbon County since 2016.
Rain
| Average year, 1991-2020 | 15.55 in |
| 12 months to August 2026 | 13.76 in (-1.79) |
| 2025 | 14.15 in (-1.40) |
| Wettest year since 1895 | 1937: 22.44 in |
| Driest year since 1895 | 1902: 9.22 in |
| Days with 1 inch or more, normal at RAWLINS MUNI AP (16 mi away) | 0.4 |
Homes
| Housing units | 8,236 |
| Median year built | 1973 |
| Built before 1980 | 67% |
| Built 2000 or later | 12% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $222,700 |
| 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 |
|---|---|---|---|
| Albany County, WY | 62 mi | 5% | 7% |
| Jackson County, CO | 78 mi | 18% | 16% |
| Routt County, CO | 84 mi | 40% | 10% |
| Natrona County, WY | 89 mi | 17% | 1% |
| Sweetwater County, WY | 101 mi | 3% | under 1% |
| Moffat County, CO | 101 mi | 10% | 1% |
| Larimer County, CO | 104 mi | 6% | 4% |
| Platte County, WY | 106 mi | under 1% | 2% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status