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Jonestown, Texas
Inside Jonestown's city limits, shrink-swell clay limits houses without basements on 2% of mapped land. A shallow water table limits basements on 0%.
That clay share is below Travis County's 39%. FEMA's flood data list 77 flood losses since 2016 in the 2 ZIP codes overlapping the city. Of its 1,321 homes, 19% were built before 1980; the median dates from 2005.
Data as of October 13, 2026 · sources · in Travis County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 2 overlapping ZIPs
of homes built before 1980
Foundation repair in Jonestown
Foundation repair in Jonestown: shrink-swell clay limits slab homes on 2% of Jonestown's mapped land.
About 1,100 of Jonestown's 1,321 homes are detached houses.
| 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 Jonestown city limits
| Expansive clay (limits slab homes) | 2.0% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 76.6% |
| Clay swell (LEP, by area) | 3.7% |
| High-swell land (LEP 6%+) | 0.5% |
| Mapped soil | 5,138 acres |
What the numbers mean here
USDA rates 77% of the land very limited for septic absorption fields.
With shrink-swell clay on 2% and a shallow water table on 0% of the land, the soil survey points to neither problem across most of Jonestown; conditions still vary lot by lot.
Drought in Travis County
100% of Travis 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 Jonestown. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78645 | 81% | 43 | $940,632 |
| 78641 | 20% | 34 | $2.1 million |
Homes in Jonestown
| Housing units | 1,321 |
| Median year built | 2005 |
| Built before 1980 | 19% |
| Built 2000 or later | 68% |
| Owner-occupied | 94% |
| Median value, owner-occupied | $557,600 |
| Single-family detached | 87% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Volente | 3 mi | 1% | 0% |
| Lago Vista | 4 mi | 4% | 0% |
| Cedar Park | 7 mi | 48% | 0% |
| Leander | 7 mi | 48% | under 1% |
| Point Venture | 8 mi | under 1% | 0% |
| Briarcliff | 9 mi | 9% | 0% |
| Lakeway | 10 mi | 9% | 0% |
| The Hills | 10 mi | 19% | 0% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status