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Trinity, Texas
Inside Trinity's city limits, shrink-swell clay limits houses without basements on 16% of mapped land. A shallow water table limits basements on 83%.
That clay share is close to Trinity County's 13%. FEMA's flood data list 37 flood losses since 2016 in ZIP code 75862 overlapping the city. Of its 1,103 homes, 40% were built before 1980; the median dates from 1984.
Data as of October 13, 2026 · sources · in Trinity 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 Trinity
Foundation repair in Trinity: shrink-swell clay limits slab homes on 16% of Trinity's mapped land.
About 500 of Trinity's 1,103 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 Trinity city limits
| Expansive clay (limits slab homes) | 16.1% |
| High water table (limits basements) | 83.2% |
| Septic fields very limited | 88.5% |
| Clay swell (LEP, by area) | 6.3% |
| High-swell land (LEP 6%+) | 68.5% |
| Mapped soil | 2,417 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Fuller | 53% | 1% |
| Herty | 18% | n/a |
| Kurth | 11% | n/a |
| Keltys | 6% | n/a |
| Rosenwall | 3% | n/a |
| Moten | 2% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 6.3% by land area here, and 68% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 16% of the mapped land.
Clay shrinks as it dries: 28% of Trinity County is in drought on the latest map, and 16% of Trinity's mapped land has shrink-swell clay.
On 83% of Trinity's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 88% of the land very limited for septic absorption fields.
Drought in Trinity County
28% of Trinity 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 Trinity. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75862 | 100% | 37 | $1.3 million |
Homes in Trinity
| Housing units | 1,103 |
| Median year built | 1984 |
| Built before 1980 | 40% |
| Built 2000 or later | 21% |
| Owner-occupied | 46% |
| Median value, owner-occupied | $94,500 |
| Single-family detached | 47% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Riverside | 7 mi | 54% | 58% |
| Lovelady | 13 mi | 42% | 74% |
| Point Blank | 17 mi | 63% | 67% |
| Groveton | 17 mi | 0% | 87% |
| Onalaska | 17 mi | 15% | 46% |
| Huntsville | 20 mi | 36% | 58% |
| Midway | 23 mi | 91% | 10% |
| Crockett | 26 mi | 43% | 45% |
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