Grimes County, Texas
Shrink-swell clay limits houses without basements on 61% of Grimes County's mapped land, a higher share than 94% of US counties. A shallow water table limits basements on 40%.
78.3% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 47 flood losses here since 2016. 24% of homes were built before 1980, against 50% nationally; the median home dates from 1997.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Grimes County
| Expansive clay (limits slab homes) | 60.7% |
| High water table (limits basements) | 40.0% |
| Septic fields very limited | 88.9% |
| Clay swell (LEP, by area) | 7.8% |
| High-swell land (LEP 6%+) | 64.6% |
| Mapped soil | 512,192 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Frelsburg | 6% | 93% |
| Shiro | 6% | n/a |
| Nahatche | 5% | n/a |
| Huntsburg | 5% | n/a |
| Zulch | 4% | n/a |
| Annona | 4% | n/a |
How we count · survey areas TX185 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 7.8% by land area here, and 65% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 61% of the mapped land.
Clay shrinks as it dries: 78.3% of the county is in drought on the latest map, and 61% of Grimes County's mapped land has shrink-swell clay.
On 40% of Grimes County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 33.03 in, 12.17 in below the 1991-2020 average year of 45.20 in.
USDA rates 89% of the land very limited for septic absorption fields.
Drought
78.3% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 38 of the last 52 weeks; the most was 100% of its area, in 18 weeks, most recently on the September 29, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 78.3% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
47 flood losses since 2016, $878,722 paid. The worst year was 2016, with 25.
| Year | Flood losses |
|---|---|
| 2016 | 25 |
| 2017 | 10 |
| 2018 | 4 |
| 2019 | 0 |
| 2020 | 1 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 6 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 45.20 in |
| 12 months to August 2026 | 33.03 in (-12.17) |
| 2025 | 38.52 in (-6.68) |
| Wettest year since 1895 | 2015: 63.84 in |
| Driest year since 1895 | 1917: 18.33 in |
| Days with 1 inch or more, normal at WASHINGTON SP (18 mi away) | 13.2 |
Homes
| Housing units | 12,349 |
| Median year built | 1997 |
| Built before 1980 | 24% |
| Built 2000 or later | 47% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $237,400 |
| Single-family detached | 71% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Grimes County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Anderson | 70% | 3% | 88 |
| Bedias | 82% | 13% | 219 |
| Iola | 94% | 3% | 230 |
| Navasota | 80% | 8% | 2,967 |
| Plantersville | 19% | 77% | 265 |
| Todd Mission | 0% | 94% | 44 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Brazos County, TX | 20 mi | 57% | 26% |
| Walker County, TX | 28 mi | 40% | 63% |
| Madison County, TX | 29 mi | 52% | 48% |
| Montgomery County, TX | 33 mi | 15% | 65% |
| Washington County, TX | 34 mi | 54% | 9% |
| Waller County, TX | 37 mi | 24% | 40% |
| Burleson County, TX | 38 mi | 50% | 17% |
| Robertson County, TX | 46 mi | 31% | 19% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status