Karnes County, Texas
Shrink-swell clay limits houses without basements on 52% of Karnes County's mapped land, a higher share than 92% 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. 40% of homes were built before 1980, against 50% nationally; the median home dates from 1988.
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 Karnes County
| Expansive clay (limits slab homes) | 52.3% |
| High water table (limits basements) | 0.1% |
| Septic fields very limited | 73.0% |
| Clay swell (LEP, by area) | 7.0% |
| High-swell land (LEP 6%+) | 54.2% |
| Mapped soil | 482,701 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Coy | 11% | n/a |
| Pernitas | 10% | n/a |
| Weesatche | 10% | n/a |
| Papalote | 7% | n/a |
| Bryde | 5% | n/a |
| Eloso | 5% | n/a |
How we count · survey areas TX255 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 7.0% by land area here, and 54% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 52% of the mapped land.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 52% of Karnes County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 24.25 in, 6.76 in below the 1991-2020 average year of 31.01 in.
USDA rates 73% 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 52 of the last 52 weeks; the most was 100% of its area, in 47 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 | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
3 flood losses since 2016, $19,770 paid. The worst year was 2020, with 2.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 0 |
| 2020 | 2 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 31.01 in |
| 12 months to August 2026 | 24.25 in (-6.76) |
| 2025 | 23.17 in (-7.84) |
| Wettest year since 1895 | 1946: 48.95 in |
| Driest year since 1895 | 1917: 11.24 in |
| Days with 1 inch or more, normal at RUNGE (10 mi away) | 9 |
Homes
| Housing units | 5,975 |
| Median year built | 1988 |
| Built before 1980 | 40% |
| Built 2000 or later | 33% |
| Owner-occupied | 62% |
| Median value, owner-occupied | $149,000 |
| Single-family detached | 66% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Karnes County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Falls City | 35% | 0% | 218 |
| Karnes City | 46% | under 1% | 1,405 |
| Kenedy | 51% | under 1% | 1,757 |
| Runge | 32% | under 1% | 566 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Wilson County, TX | 23 mi | 36% | 2% |
| Goliad County, TX | 31 mi | 24% | 21% |
| DeWitt County, TX | 32 mi | 27% | 17% |
| Bee County, TX | 35 mi | 25% | 11% |
| Atascosa County, TX | 41 mi | 34% | under 1% |
| Live Oak County, TX | 42 mi | 29% | under 1% |
| Gonzales County, TX | 44 mi | 55% | 5% |
| Guadalupe County, TX | 47 mi | 52% | 8% |
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