St. Clair County, Alabama
USDA's soil survey flags shrink-swell clay on 0% of St. Clair County's mapped land and a shallow water table under basements on 12%, both below the national shares of 15% and 29%. None of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 11 flood losses here since 2016. 23% of homes were built before 1980, against 50% nationally; the median home dates from 1998.
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 St. Clair County
| Expansive clay (limits slab homes) | 0.0% |
| High water table (limits basements) | 12.3% |
| Septic fields very limited | 73.3% |
| Clay swell (LEP, by area) | 2.7% |
| High-swell land (LEP 6%+) | 4.8% |
| Mapped soil | 418,020 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Townley | 21% | n/a |
| Minvale | 18% | n/a |
| Nauvoo | 18% | n/a |
| Conasauga | 5% | n/a |
| Firestone | 5% | n/a |
| Nella | 5% | n/a |
How we count · survey areas AL115 (2025-09-10)
What the numbers mean here
Rain over the 12 months to August 2026: 50.64 in, 5.84 in below the 1991-2020 average year of 56.48 in.
USDA rates 73% of the land very limited for septic absorption fields.
With shrink-swell clay on 0% and a shallow water table on 12% of the land, the soil survey points to neither problem across most of St. Clair County; conditions still vary lot by lot.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 22 of the last 52 weeks; the most was 100% of its area, in 9 weeks, most recently on the May 19, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
11 flood losses since 2016, $657,174 paid. The worst year was 2021, with 3.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 3 |
| 2020 | 2 |
| 2021 | 3 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 56.48 in |
| 12 months to August 2026 | 50.64 in (-5.84) |
| 2025 | 54.83 in (-1.65) |
| Wettest year since 1895 | 1929: 75.26 in |
| Driest year since 1895 | 2007: 29.67 in |
| Days with 1 inch or more, normal at LEEDS (21 mi away) | 21 |
Homes
| Housing units | 39,247 |
| Median year built | 1998 |
| Built before 1980 | 23% |
| Built 2000 or later | 47% |
| Owner-occupied | 83% |
| Median value, owner-occupied | $226,300 |
| Single-family detached | 72% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Blount County, AL | 23 mi | 9% | 10% |
| Talladega County, AL | 25 mi | 1% | 20% |
| Etowah County, AL | 28 mi | 4% | 15% |
| Calhoun County, AL | 28 mi | 7% | 20% |
| Jefferson County, AL | 36 mi | 2% | 3% |
| Shelby County, AL | 37 mi | 2% | 9% |
| Clay County, AL | 40 mi | 2% | 15% |
| Marshall County, AL | 41 mi | 6% | 22% |
Sources: USDA SSURGO (September 10, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status