Dimmit County, Texas
Shrink-swell clay limits houses without basements on 30% of Dimmit County's mapped land, a higher share than 81% of US counties. A shallow water table limits basements on under 1%.
100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 3 flood losses here since 2016. 43% of homes were built before 1980, against 50% nationally; the median home dates from 1985.
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 Dimmit County
| Expansive clay (limits slab homes) | 30.5% |
| High water table (limits basements) | 0.2% |
| Septic fields very limited | 58.9% |
| Clay swell (LEP, by area) | 5.5% |
| High-swell land (LEP 6%+) | 28.0% |
| Mapped soil | 837,273 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Brundage | 10% | n/a |
| Maverick | 10% | n/a |
| Duval | 9% | n/a |
| Tonio | 6% | n/a |
| Brystal | 6% | n/a |
| Pryor | 6% | n/a |
How we count · survey areas TX605 (2025-09-05)
What the numbers mean here
Clay swell averages a linear extensibility of 5.5% by land area here, and 28% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 30% of the mapped land.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 30% of Dimmit County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 16.84 in, 3.65 in below the 1991-2020 average year of 20.49 in.
USDA rates 59% 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 46 of the last 52 weeks; the most was 100% of its area, in 41 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 | 100% |
| D3 extreme or worse | 52.2% |
| D4 exceptional | 0% |
Flood losses since 2016
3 flood losses since 2016, $318,313 paid. The worst year was 2026, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 20.49 in |
| 12 months to August 2026 | 16.84 in (-3.65) |
| 2025 | 14.24 in (-6.25) |
| Wettest year since 1895 | 1919: 39.14 in |
| Driest year since 1895 | 1917: 7.34 in |
| Days with 1 inch or more, normal at CARRIZO SPRINGS 3S (8 mi away) | 5.5 |
Homes
| Housing units | 4,023 |
| Median year built | 1985 |
| Built before 1980 | 43% |
| Built 2000 or later | 34% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $85,500 |
| Single-family detached | 63% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Dimmit County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Asherton | 8% | 0% | 396 |
| Big Wells | 47% | under 1% | 236 |
| Carrizo Springs | 3% | under 1% | 2,194 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Zavala County, TX | 30 mi | 28% | under 1% |
| Maverick County, TX | 40 mi | 33% | under 1% |
| La Salle County, TX | 41 mi | 35% | under 1% |
| Frio County, TX | 50 mi | 10% | under 1% |
| Webb County, TX | 54 mi | 33% | under 1% |
| Uvalde County, TX | 64 mi | 23% | under 1% |
| McMullen County, TX | 72 mi | 35% | under 1% |
| Kinney County, TX | 75 mi | 10% | 1% |
Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status