Iola, Texas
Inside Iola's city limits, shrink-swell clay limits houses without basements on 94% of mapped land, the highest of 6 cities in Grimes County. A shallow water table limits basements on 3%, the 5th-highest of 6 cities in Grimes County.
That clay share is above Grimes County's 61%. FEMA's flood data list 4 flood losses since 2016 in ZIP code 77861 overlapping the city. Of its 230 homes, 39% were built before 1980; the median dates from 1987.
Data as of October 13, 2026 · sources · in Grimes 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 Iola
Foundation repair in Iola: shrink-swell clay limits slab homes on 94% of Iola's mapped land, more than in 98% of Texas cities.
About 200 of Iola's 230 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 Iola city limits
| Expansive clay (limits slab homes) | 93.9% |
| High water table (limits basements) | 3.2% |
| Septic fields very limited | 95.6% |
| Clay swell (LEP, by area) | 7.5% |
| High-swell land (LEP 6%+) | 94.9% |
| Mapped soil | 665 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Zulch | 69% | n/a |
| Zack | 24% | n/a |
| Gredge | 3% | n/a |
| Boonville | 3% | n/a |
| Nahatche | 1% | n/a |
| Chazos | under 1% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 7.5% by land area here, and 95% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 94% of the mapped land.
Clay shrinks as it dries: 78.3% of Grimes County is in drought on the latest map, and 94% of Iola's mapped land has shrink-swell clay.
USDA rates 96% of the land very limited for septic absorption fields.
Drought in Grimes County
78.3% of Grimes 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 Iola. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 77861 | 100% | 4 | $86,149 |
Homes in Iola
| Housing units | 230 |
| Median year built | 1987 |
| Built before 1980 | 39% |
| Built 2000 or later | 28% |
| Owner-occupied | 75% |
| Median value, owner-occupied | $133,300 |
| Single-family detached | 73% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Bedias | 8 mi | 82% | 13% |
| Kurten | 12 mi | 72% | 53% |
| Wixon Valley | 14 mi | 73% | 42% |
| Madisonville | 16 mi | 79% | 31% |
| Normangee | 18 mi | 79% | 9% |
| College Station | 18 mi | 57% | 23% |
| Bryan | 19 mi | 56% | 22% |
| Anderson | 20 mi | 70% | 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