Franklin County, Missouri
A shallow water table limits basements on 61% of Franklin County's mapped land, a higher share than 74% of US counties. Shrink-swell clay limits houses without basements on 14%.
30% of the county is in drought on the October 13, 2026 Drought Monitor map, up from 0% a week earlier. FEMA's flood data list 181 flood losses here since 2016, 17% of them in buildings with basements. 44% of homes were built before 1980, against 50% nationally; the median home dates from 1984.
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 Franklin County
| Expansive clay (limits slab homes) | 13.9% |
| High water table (limits basements) | 60.6% |
| Septic fields very limited | 95.3% |
| Clay swell (LEP, by area) | 4.9% |
| High-swell land (LEP 6%+) | 22.6% |
| Mapped soil | 595,226 acres |
How we count · survey areas MO071 (2025-09-02)
What the numbers mean here
On 61% of Franklin 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: 40.49 in, 2.63 in below the 1991-2020 average year of 43.12 in.
USDA rates 95% of the land very limited for septic absorption fields.
Drought
30% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 18 of the last 52 weeks; the most was 100% of its area, in 6 weeks, most recently on the February 10, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 30% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
181 flood losses since 2016, $8.4 million paid. The worst year was 2017, with 153. Foundations of the buildings, where recorded: 17% basements, 17% slabs, 15% crawl spaces, 52% elevated. Median water depth outside the building: 62 in.
| Year | Flood losses |
|---|---|
| 2016 | 3 |
| 2017 | 153 |
| 2018 | 0 |
| 2019 | 4 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 18 |
| 2025 | 1 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 43.12 in |
| 12 months to August 2026 | 40.49 in (-2.63) |
| 2025 | 38.26 in (-4.86) |
| Wettest year since 1895 | 1993: 64.54 in |
| Driest year since 1895 | 1976: 23.37 in |
| Days with 1 inch or more, normal at WASHINGTON (10 mi away) | 12 |
Homes
| Housing units | 46,312 |
| Median year built | 1984 |
| Built before 1980 | 44% |
| Built 2000 or later | 27% |
| Owner-occupied | 77% |
| Median value, owner-occupied | $227,600 |
| Single-family detached | 76% |
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 |
|---|---|---|---|
| Gasconade County, MO | 23 mi | 37% | 76% |
| Warren County, MO | 25 mi | 52% | 59% |
| Jefferson County, MO | 31 mi | 37% | 34% |
| St. Charles County, MO | 33 mi | 41% | 62% |
| Crawford County, MO | 33 mi | 15% | 34% |
| Washington County, MO | 34 mi | 27% | 25% |
| St. Louis County, MO | 37 mi | 5% | 37% |
| Montgomery County, MO | 42 mi | 67% | 76% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status