Galveston County, Texas
Shrink-swell clay limits houses without basements on 23% of Galveston County's mapped land, a higher share than 73% of US counties. A shallow water table limits basements on 61%.
27% of the county is in drought on the September 22, 2026 Drought Monitor map, down from 84.8% a week earlier. FEMA's flood data list 10,476 flood losses here since 2016, under 1% of them in buildings with basements. 36% of homes were built before 1980, against 50% nationally; the median home dates from 1990.
Data as of September 22, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, September 22, 2026
of homes built before 1980
Soil under Galveston County
| Expansive clay (limits slab homes) | 22.6% |
| High water table (limits basements) | 61.5% |
| Septic fields very limited | 48.2% |
| Clay swell (LEP, by area) | 5.2% |
| High-swell land (LEP 6%+) | 23.1% |
| Urban land, not rated | 2.2% |
| Mapped soil | 429,774 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Bernard | 7% | 43% |
| Lake Charles | 7% | 97% |
| Maggies | 5% | n/a |
| Mocarey | 4% | n/a |
| Danacove | 4% | n/a |
| Galveston | 3% | n/a |
How we count · survey areas TX167 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 5.2% by land area here, and 23% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 23% of the mapped land.
Clay shrinks as it dries: 27% of the county is in drought on the latest map, and 23% of Galveston County's mapped land has shrink-swell clay.
On 61% of Galveston 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: 41.26 in, 12.40 in below the 1991-2020 average year of 53.66 in.
Drought
27% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 33 of the last 52 weeks; the most was 100% of its area, in 15 weeks, most recently on the April 14, 2026 map.
| Category, September 22, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 27% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
10,476 flood losses since 2016, $860.9 million paid. The worst year was 2017, with 8,853. Foundations of the buildings, where recorded: under 1% basements, 79% slabs, 2% crawl spaces, 19% elevated. Median water depth outside the building: 14 in.
| Year | Flood losses |
|---|---|
| 2016 | 104 |
| 2017 | 8,853 |
| 2018 | 163 |
| 2019 | 121 |
| 2020 | 171 |
| 2021 | 223 |
| 2022 | 20 |
| 2023 | 15 |
| 2024 | 789 |
| 2025 | 9 |
| 2026 to date | 8 |
Rain
| Average year, 1991-2020 | 53.66 in |
| 12 months to August 2026 | 41.26 in (-12.40) |
| 2025 | 36.25 in (-17.41) |
| Wettest year since 1895 | 1900: 79.59 in |
| Driest year since 1895 | 1917: 22.63 in |
| Days with 1 inch or more, normal at HOUSTON NWSO (20 mi away) | 18.8 |
Homes
| Housing units | 161,868 |
| Median year built | 1990 |
| Built before 1980 | 36% |
| Built 2000 or later | 38% |
| Owner-occupied | 68% |
| Median value, owner-occupied | $314,600 |
| Single-family detached | 72% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Galveston County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Bayou Vista | 35% | 68% | 1,151 |
| Clear Lake Shores | 16% | 57% | 584 |
| Dickinson | 66% | 74% | 8,291 |
| Friendswood | 74% | 49% | 15,553 |
| Galveston | 1% | 91% | 35,776 |
| Hitchcock | 40% | 94% | 2,980 |
| Jamaica Beach | under 1% | 75% | 1,452 |
| Kemah | 20% | 93% | 1,019 |
| La Marque | 61% | 64% | 8,083 |
| League City | 42% | 71% | 44,942 |
| Santa Fe | 6% | 92% | 5,131 |
| Texas City | 16% | 32% | 23,618 |
| Tiki Island | 5% | 68% | 1,161 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Brazoria County, TX | 33 mi | 64% | 44% |
| Chambers County, TX | 34 mi | 63% | 68% |
| Harris County, TX | 53 mi | 25% | 53% |
| Fort Bend County, TX | 57 mi | 64% | 42% |
| Jefferson County, TX | 62 mi | 56% | 66% |
| Liberty County, TX | 66 mi | 46% | 76% |
| Matagorda County, TX | 74 mi | 62% | 28% |
| Wharton County, TX | 81 mi | 68% | 32% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status