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San Diego, Texas
Inside San Diego's city limits, shrink-swell clay limits houses without basements on 36% of mapped land, the highest of 3 cities in Duval County. A shallow water table limits basements on 2%, the highest of 3 cities in Duval County.
That clay share is above Duval County's 4%. FEMA's flood data list no flood losses since 2016 in ZIP code 78384 overlapping the city. Of its 1,736 homes, 64% were built before 1980; the median dates from 1969.
Data as of October 13, 2026 · sources · in Duval County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 1 overlapping ZIP
of homes built before 1980
Foundation repair in San Diego
Foundation repair in San Diego: shrink-swell clay limits slab homes on 36% of San Diego's mapped land.
About 1,400 of San Diego's 1,736 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 San Diego city limits
| Expansive clay (limits slab homes) | 35.8% |
| High water table (limits basements) | 2.4% |
| Septic fields very limited | 26.1% |
| Clay swell (LEP, by area) | 4.3% |
| High-swell land (LEP 6%+) | 13.1% |
| Mapped soil | 1,218 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Czar | 26% | n/a |
| Clareville | 12% | n/a |
| Racombes | 10% | n/a |
| Premont | 9% | n/a |
| Gertrudis | 9% | n/a |
| Sinton | 8% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 4.3% by land area here, and 13% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 36% of the mapped land.
Clay shrinks as it dries: 100% of Duval County is in drought on the latest map, and 36% of San Diego's mapped land has shrink-swell clay.
Drought in Duval County
100% of Duval 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 San Diego. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78384 | over 99% | 0 | $0 |
Homes in San Diego
| Housing units | 1,736 |
| Median year built | 1969 |
| Built before 1980 | 64% |
| Built 2000 or later | 14% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $85,600 |
| Single-family detached | 82% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Alice | 11 mi | 49% | 14% |
| Benavides | 16 mi | 10% | under 1% |
| Agua Dulce | 20 mi | 97% | 1% |
| Orange Grove | 23 mi | 82% | under 1% |
| Freer | 25 mi | 3% | under 1% |
| Premont | 29 mi | 49% | 24% |
| Kingsville | 29 mi | 62% | 1% |
| Bishop | 30 mi | 96% | 3% |
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