Mason County, Texas
Shrink-swell clay limits houses without basements on 15% of Mason County's mapped land, a higher share than 63% of US counties. A shallow water table limits basements on 0%.
1.7% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 2 flood losses here since 2016. 54% of homes were built before 1980, against 50% nationally; the median home dates from 1976.
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 Mason County
| Expansive clay (limits slab homes) | 15.0% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 78.2% |
| Clay swell (LEP, by area) | 3.2% |
| High-swell land (LEP 6%+) | 9.8% |
| Mapped soil | 597,459 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Eckert | 13% | n/a |
| Keese | 9% | n/a |
| Castell | 5% | n/a |
| Nebgen | 5% | n/a |
| Tarrant | 4% | n/a |
| Voca | 4% | n/a |
How we count · survey areas TX319 (2025-09-04)
What the numbers mean here
Rain over the 12 months to August 2026: 32.66 in, 4.70 in above the 1991-2020 average year of 27.96 in.
USDA rates 78% of the land very limited for septic absorption fields.
With shrink-swell clay on 15% and a shallow water table on 0% of the land, the soil survey points to neither problem across most of Mason County; conditions still vary lot by lot.
Drought
1.7% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 9 of the last 52 weeks; the most was 98.7% of its area, in 2 weeks, most recently on the November 18, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 25.7% |
| D1 moderate drought or worse | 1.7% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
2 flood losses since 2016, $90,000 paid. The worst year was 2018, with 2.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 2 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 27.96 in |
| 12 months to August 2026 | 32.66 in (+4.70) |
| 2025 | 31.29 in (+3.33) |
| Wettest year since 1895 | 1919: 50.68 in |
| Driest year since 1895 | 1954: 10.85 in |
| Days with 1 inch or more, normal at TAYLOR RCH (25 mi away) | 8.9 |
Homes
| Housing units | 2,430 |
| Median year built | 1976 |
| Built before 1980 | 54% |
| Built 2000 or later | 24% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $293,600 |
| Single-family detached | 81% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Mason County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Mason | 25% | 0% | 987 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Gillespie County, TX | 32 mi | 23% | 0% |
| Llano County, TX | 33 mi | 16% | 0% |
| Kimble County, TX | 34 mi | 6% | 0% |
| McCulloch County, TX | 35 mi | 29% | under 1% |
| Menard County, TX | 39 mi | 12% | 0% |
| San Saba County, TX | 40 mi | 45% | 1% |
| Kerr County, TX | 46 mi | 33% | under 1% |
| Concho County, TX | 56 mi | 32% | under 1% |
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