Blanco County, Texas
Shrink-swell clay limits houses without basements on 28% of Blanco County's mapped land, a higher share than 78% of US counties. A shallow water table limits basements on 0%.
19.9% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 26% of homes were built before 1980, against 50% nationally; the median home dates from 1998.
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 Blanco County
| Expansive clay (limits slab homes) | 27.6% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 84.4% |
| Clay swell (LEP, by area) | 4.8% |
| High-swell land (LEP 6%+) | 23.7% |
| Mapped soil | 456,653 acres |
How we count · survey areas TX601 (2025-09-05)
What the numbers mean here
Clay swell averages a linear extensibility of 4.8% by land area here, and 24% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 28% of the mapped land.
Clay shrinks as it dries: 19.9% of the county is in drought on the latest map, and 28% of Blanco County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 29.44 in, 3.61 in below the 1991-2020 average year of 33.05 in.
USDA rates 84% of the land very limited for septic absorption fields.
Drought
19.9% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 44 of the last 52 weeks; the most was 100% of its area, in 30 weeks, most recently on the June 2, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 19.9% |
| 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 Blanco County since 2016.
Rain
| Average year, 1991-2020 | 33.05 in |
| 12 months to August 2026 | 29.44 in (-3.61) |
| 2025 | 29.89 in (-3.16) |
| Wettest year since 1895 | 1919: 54.67 in |
| Driest year since 1895 | 1954: 11.44 in |
| Days with 1 inch or more, normal at HYE (10 mi away) | 10.2 |
Homes
| Housing units | 6,129 |
| Median year built | 1998 |
| Built before 1980 | 26% |
| Built 2000 or later | 47% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $483,500 |
| Single-family detached | 81% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Blanco County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Blanco | 28% | 0% | 989 |
| Johnson City | 51% | 0% | 968 |
| Round Mountain | 31% | 0% | 51 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Hays County, TX | 26 mi | 14% | under 1% |
| Kendall County, TX | 29 mi | 23% | 0% |
| Comal County, TX | 32 mi | 19% | under 1% |
| Gillespie County, TX | 33 mi | 23% | 0% |
| Llano County, TX | 35 mi | 16% | 0% |
| Burnet County, TX | 38 mi | 27% | 0% |
| Travis County, TX | 42 mi | 39% | under 1% |
| Williamson County, TX | 54 mi | 60% | 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