Castro County, Texas
Shrink-swell clay limits houses without basements on 82% of Castro County's mapped land, a higher share than 99% of US counties and the 4th highest of 254 Texas counties. A shallow water table limits basements on 5%.
1.7% of the county is in drought on the October 13, 2026 Drought Monitor map, down from 100% a week earlier. FEMA's flood data list no flood losses here since 2016. 69% 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 Castro County
| Expansive clay (limits slab homes) | 82.4% |
| High water table (limits basements) | 4.8% |
| Septic fields very limited | 77.7% |
| Clay swell (LEP, by area) | 5.9% |
| High-swell land (LEP 6%+) | 75.5% |
| Mapped soil | 575,565 acres |
How we count · survey areas TX069 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 5.9% by land area here, and 76% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 82% of the mapped land.
Clay shrinks as it dries: 1.7% of the county is in drought on the latest map, and 82% of Castro County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 10.67 in, 8.60 in below the 1991-2020 average year of 19.27 in.
USDA rates 78% of the land very limited for septic absorption fields.
Drought
1.7% 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 28 weeks, most recently on the October 6, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 1.7% |
| 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 Castro County since 2016.
Rain
| Average year, 1991-2020 | 19.27 in |
| 12 months to August 2026 | 10.67 in (-8.60) |
| 2025 | 20.45 in (+1.18) |
| Wettest year since 1895 | 1941: 39.10 in |
| Driest year since 1895 | 2011: 8.47 in |
| Days with 1 inch or more, normal at DIMMITT 2 N (5 mi away) | 5.4 |
Homes
| Housing units | 3,024 |
| Median year built | 1966 |
| Built before 1980 | 69% |
| Built 2000 or later | 11% |
| Owner-occupied | 64% |
| Median value, owner-occupied | $95,000 |
| Single-family detached | 75% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Castro County
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Swisher County, TX | 29 mi | 87% | 10% |
| Parmer County, TX | 30 mi | 61% | 2% |
| Lamb County, TX | 32 mi | 14% | 2% |
| Deaf Smith County, TX | 34 mi | 70% | 3% |
| Randall County, TX | 36 mi | 66% | 7% |
| Hale County, TX | 41 mi | 83% | 7% |
| Bailey County, TX | 46 mi | 3% | 2% |
| Armstrong County, TX | 59 mi | 45% | 6% |
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