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College Station, Texas
Inside College Station's city limits, shrink-swell clay limits houses without basements on 57% of mapped land, the 3rd-highest of 4 cities in Brazos County. A shallow water table limits basements on 23%, the 3rd-highest of 4 cities in Brazos County.
That clay share is close to Brazos County's 57%. FEMA's flood data list 83 flood losses since 2016 in the 3 ZIP codes overlapping the city. Of its 51,494 homes, 18% were built before 1980; the median dates from 1999.
Data as of September 22, 2026 · sources · in Brazos County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 3 overlapping ZIPs
of homes built before 1980
Soil under College Station city limits
| Expansive clay (limits slab homes) | 57.5% |
| High water table (limits basements) | 23.1% |
| Septic fields very limited | 88.2% |
| Clay swell (LEP, by area) | 7.2% |
| High-swell land (LEP 6%+) | 62.2% |
| Urban land, not rated | 14.1% |
| Mapped soil | 32,830 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Boonville | 15% | n/a |
| Zack | 10% | n/a |
| Sandow | 9% | n/a |
| Burlewash | 8% | n/a |
| Singleton | 8% | n/a |
| Tabor | 6% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 7.2% by land area here, and 62% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 57% of the mapped land.
Clay shrinks as it dries: 99.4% of Brazos County is in drought on the latest map, and 57% of College Station's mapped land has shrink-swell clay.
On 23% of College Station'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 Brazos County
99.4% of Brazos County is in drought (D1 or worse) on the September 22, 2026 map.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap College Station. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 77845 | 80% | 23 | $376,299 |
| 77840 | 19% | 60 | $195,853 |
| 77843 | 1% | 0 | $0 |
Homes in College Station
| Housing units | 51,494 |
| Median year built | 1999 |
| Built before 1980 | 18% |
| Built 2000 or later | 48% |
| Owner-occupied | 35% |
| Median value, owner-occupied | $346,700 |
| Single-family detached | 42% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Bryan | 8 mi | 56% | 22% |
| Snook | 12 mi | 70% | 15% |
| Wixon Valley | 12 mi | 73% | 42% |
| Kurten | 14 mi | 72% | 53% |
| Iola | 18 mi | 94% | 3% |
| Navasota | 18 mi | 80% | 8% |
| Anderson | 19 mi | 70% | 3% |
| Somerville | 22 mi | 60% | 30% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status