Guadalupe County, Texas
Shrink-swell clay limits houses without basements on 52% of Guadalupe County's mapped land, a higher share than 92% of US counties. A shallow water table limits basements on 8%.
100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 40 flood losses here since 2016, 0% of them in buildings with basements. 19% of homes were built before 1980, against 50% nationally; the median home dates from 2003.
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 Guadalupe County
| Expansive clay (limits slab homes) | 52.4% |
| High water table (limits basements) | 8.3% |
| Septic fields very limited | 79.6% |
| Clay swell (LEP, by area) | 7.9% |
| High-swell land (LEP 6%+) | 52.2% |
| Mapped soil | 457,638 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Crockett | 12% | 94% |
| Houston Black | 11% | 91% |
| Branyon | 11% | 92% |
| Heiden | 8% | 80% |
| Patilo | 6% | n/a |
| Arenosa | 4% | n/a |
How we count · survey areas TX187 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 7.9% by land area here, and 52% 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 Guadalupe County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 28.80 in, 4.44 in below the 1991-2020 average year of 33.24 in.
USDA rates 80% 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 40 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 | 71.8% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
40 flood losses since 2016, $580,358 paid. The worst year was 2021, with 14. Foundations of the buildings, where recorded: 82% slabs, 7% crawl spaces, 11% elevated.
| Year | Flood losses |
|---|---|
| 2016 | 7 |
| 2017 | 8 |
| 2018 | 0 |
| 2019 | 3 |
| 2020 | 1 |
| 2021 | 14 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 5 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 33.24 in |
| 12 months to August 2026 | 28.80 in (-4.44) |
| 2025 | 26.31 in (-6.93) |
| Wettest year since 1895 | 1919: 54.56 in |
| Driest year since 1895 | 1954: 14.73 in |
| Days with 1 inch or more, normal at SEGUIN 1 SSW (2 mi away) | 10.3 |
Homes
| Housing units | 69,700 |
| Median year built | 2003 |
| Built before 1980 | 19% |
| Built 2000 or later | 56% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $304,400 |
| Single-family detached | 77% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Guadalupe County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Cibolo | 78% | under 1% | 11,650 |
| Kingsbury | 35% | 12% | 59 |
| Marion | 84% | under 1% | 431 |
| New Berlin | 69% | 1% | 255 |
| Santa Clara | 82% | under 1% | 251 |
| Schertz | 63% | under 1% | 16,573 |
| Seguin | 74% | 2% | 13,397 |
| Staples | 83% | under 1% | 116 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Comal County, TX | 24 mi | 19% | under 1% |
| Caldwell County, TX | 26 mi | 59% | 6% |
| Gonzales County, TX | 29 mi | 55% | 5% |
| Wilson County, TX | 29 mi | 36% | 2% |
| Hays County, TX | 33 mi | 14% | under 1% |
| Bexar County, TX | 36 mi | 51% | under 1% |
| Karnes County, TX | 47 mi | 52% | under 1% |
| Travis County, TX | 48 mi | 39% | under 1% |
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