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Round Mountain, Texas
Inside Round Mountain's city limits, shrink-swell clay limits houses without basements on 31% of mapped land, the 2nd-highest of 3 cities in Blanco County. A shallow water table limits basements on 0%.
That clay share is close to Blanco County's 28%. FEMA's flood data list no flood losses since 2016 in ZIP code 78663 overlapping the city.
Data as of October 13, 2026 · sources · in Blanco County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 1 overlapping ZIP
Foundation repair in Round Mountain
Foundation repair in Round Mountain: shrink-swell clay limits slab homes on 31% of Round Mountain's mapped land.
| Who designs the repair | The ASCE Texas Section's repair guidelines say a Texas-licensed engineer should evaluate the foundation and design the repair (2022 guidelines) |
| Prices | Cost guide ranges compared |
Soil under Round Mountain city limits
| Expansive clay (limits slab homes) | 30.8% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 84.9% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 20.9% |
| Mapped soil | 1,468 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Brackett | 38% | 0% |
| Hensley | 13% | n/a |
| Pedernales | 11% | n/a |
| Doss | 9% | n/a |
| Krum | 9% | n/a |
| Bolar | 5% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 21% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 31% of the mapped land.
Clay shrinks as it dries: 19.9% of Blanco County is in drought on the latest map, and 31% of Round Mountain's mapped land has shrink-swell clay.
USDA rates 85% of the land very limited for septic absorption fields.
Drought in Blanco County
19.9% of Blanco County is in drought (D1 or worse) on the October 13, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Round Mountain. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78663 | 92% | 0 | $0 |
Homes
Round Mountain has fewer than 100 housing units in the ACS 2020-2024 estimates, too few for reliable shares.
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Johnson City | 9 mi | 51% | 0% |
| Horseshoe Bay | 10 mi | 10% | 0% |
| Double Horn | 11 mi | 70% | 0% |
| Cottonwood Shores | 11 mi | 20% | 0% |
| Meadowlakes | 12 mi | 64% | 0% |
| Marble Falls | 12 mi | 44% | under 1% |
| Granite Shoals | 13 mi | 0% | 0% |
| Sunrise Beach Village | 14 mi | 1% | 0% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026). Methods · Data status