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Port Isabel, Texas
Inside Port Isabel's city limits, shrink-swell clay limits houses without basements on 7% of mapped land. A shallow water table limits basements on 54%, the 2nd-highest of 19 cities in Cameron County.
That clay share is below Cameron County's 29%. FEMA's flood data list 22 flood losses since 2016 in ZIP code 78578 overlapping the city. Of its 2,661 homes, 47% were built before 1980; the median dates from 1982.
Data as of October 13, 2026 · sources · in Cameron 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 Port Isabel
Foundation repair in Port Isabel: shrink-swell clay limits slab homes on 7% of Port Isabel's mapped land.
About 1,100 of Port Isabel's 2,661 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 Port Isabel city limits
| Expansive clay (limits slab homes) | 7.4% |
| High water table (limits basements) | 53.6% |
| Septic fields very limited | 61.1% |
| Clay swell (LEP, by area) | 6.1% |
| High-swell land (LEP 6%+) | 27.6% |
| Mapped soil | 20,827 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Barrada | 21% | n/a |
| Sejita | 19% | n/a |
| Point Isabel | 10% | n/a |
| Lomalta | 9% | n/a |
| Laredo | 4% | 0% |
| Arrada | 1% | n/a |
What the numbers mean here
On 54% of Port Isabel's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 61% of the land very limited for septic absorption fields.
Drought in Cameron County
83.8% of Cameron 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 Port Isabel. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78578 | 100% | 22 | $239,676 |
Homes in Port Isabel
| Housing units | 2,661 |
| Median year built | 1982 |
| Built before 1980 | 47% |
| Built 2000 or later | 20% |
| Owner-occupied | 60% |
| Median value, owner-occupied | $182,600 |
| Single-family detached | 42% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Laguna Vista | 3 mi | 34% | 64% |
| Bayview | 7 mi | 27% | 3% |
| Starbase | 9 mi | 8% | 49% |
| South Padre Island | 9 mi | 0% | 50% |
| Los Fresnos | 11 mi | 45% | 10% |
| Brownsville | 12 mi | 41% | 31% |
| Indian Lake | 12 mi | 15% | 0% |
| Rancho Viejo | 15 mi | 26% | 5% |
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