Natrona County, Wyoming
Shrink-swell clay limits houses without basements on 17% of Natrona County's mapped land, a higher share than 66% of US counties and the 7th highest of 22 Wyoming counties. A shallow water table limits basements on 1%.
100% 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. 55% of homes were built before 1980, against 50% nationally; the median home dates from 1977.
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 Natrona County
| Expansive clay (limits slab homes) | 17.2% |
| High water table (limits basements) | 0.9% |
| Septic fields very limited | 58.2% |
| Clay swell (LEP, by area) | 3.9% |
| High-swell land (LEP 6%+) | 18.6% |
| Mapped soil | 3,431,080 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Hiland | 6% | n/a |
| Keyner | 3% | n/a |
| Orpha | 3% | n/a |
| Shingle | 3% | n/a |
| Forkwood | 2% | n/a |
| Rock River | 2% | n/a |
How we count · survey areas WY625 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 3.9% by land area here, and 19% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 17% of the mapped land.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 17% of Natrona County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 9.94 in, 2.13 in below the 1991-2020 average year of 12.07 in.
USDA rates 58% of the land very limited for septic absorption fields.
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 37 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 | 64.2% |
| D3 extreme or worse | 33.5% |
| D4 exceptional | 0% |
Flood losses since 2016
7 flood losses since 2016, $128,327 paid. The worst year was 2023, with 2.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 1 |
| 2018 | 1 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 1 |
| 2023 | 2 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 12.07 in |
| 12 months to August 2026 | 9.94 in (-2.13) |
| 2025 | 11.85 in (-0.22) |
| Wettest year since 1895 | 1915: 17.78 in |
| Driest year since 1895 | 2020: 6.51 in |
| Days with 1 inch or more, normal at CASPER NATRONA CO AP (17 mi away) | 0.8 |
Homes
| Housing units | 37,309 |
| Median year built | 1977 |
| Built before 1980 | 55% |
| Built 2000 or later | 28% |
| Owner-occupied | 74% |
| Median value, owner-occupied | $273,000 |
| 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 |
|---|---|---|---|
| Converse County, WY | 63 mi | 16% | 1% |
| Johnson County, WY | 74 mi | 18% | 1% |
| Washakie County, WY | 77 mi | 5% | 2% |
| Carbon County, WY | 89 mi | 9% | 5% |
| Fremont County, WY | 93 mi | 4% | 3% |
| Hot Springs County, WY | 98 mi | 17% | 3% |
| Campbell County, WY | 104 mi | 22% | 1% |
| Albany County, WY | 106 mi | 5% | 7% |
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