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San Juan, Texas
Inside San Juan's city limits, shrink-swell clay limits houses without basements on 32% of mapped land. A shallow water table limits basements on 1%.
That clay share is above Hidalgo County's 12%. FEMA's flood data list 35 flood losses since 2016 in ZIP code 78589 overlapping the city. Of its 11,342 homes, 18% were built before 1980; the median dates from 1999.
Data as of October 13, 2026 · sources · in Hidalgo 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 Juan
Foundation repair in San Juan: shrink-swell clay limits slab homes on 32% of San Juan's mapped land.
About 9,200 of San Juan's 11,342 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 Juan city limits
| Expansive clay (limits slab homes) | 32.1% |
| High water table (limits basements) | 1.1% |
| Septic fields very limited | 33.7% |
| Clay swell (LEP, by area) | 5.8% |
| High-swell land (LEP 6%+) | 32.1% |
| Urban land, not rated | 4.8% |
| Mapped soil | 7,761 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Hidalgo | 48% | 0% |
| Raymondville | 24% | n/a |
| Harlingen | 9% | n/a |
| Racombes | 3% | n/a |
| Runn | 2% | n/a |
| Willacy | 1% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 5.8% by land area here, and 32% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 32% of the mapped land.
Clay shrinks as it dries: 100% of Hidalgo County is in drought on the latest map, and 32% of San Juan's mapped land has shrink-swell clay.
Drought in Hidalgo County
100% of Hidalgo 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 Juan. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78589 | 100% | 35 | $640,913 |
Homes in San Juan
| Housing units | 11,342 |
| Median year built | 1999 |
| Built before 1980 | 18% |
| Built 2000 or later | 48% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $126,700 |
| Single-family detached | 81% |
Nearby cities
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