Clark County, Missouri
A shallow water table limits basements on 78% of Clark County's mapped land, a higher share than 87% of US counties. Shrink-swell clay limits houses without basements on 58%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 30 flood losses here since 2016. 68% of homes were built before 1980, against 50% nationally; the median home dates from 1970.
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 Clark County
| Expansive clay (limits slab homes) | 58.5% |
| High water table (limits basements) | 78.1% |
| Septic fields very limited | 98.5% |
| Clay swell (LEP, by area) | 6.8% |
| High-swell land (LEP 6%+) | 58.4% |
| Mapped soil | 327,911 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Armstrong | 17% | over 99% |
| Lindley | 12% | n/a |
| Adco | 12% | n/a |
| Keswick | 8% | n/a |
| Gorin | 5% | n/a |
| Leonard | 5% | n/a |
How we count · survey areas MO045 (2025-09-03)
What the numbers mean here
Clay swell averages a linear extensibility of 6.8% by land area here, and 58% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 58% of the mapped land.
On 78% of Clark 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: 33.26 in, 5.90 in below the 1991-2020 average year of 39.16 in.
USDA rates 98% of the land very limited for septic absorption fields.
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 7 weeks, most recently on the March 31, 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
30 flood losses since 2016, $5.2 million paid. The worst year was 2019, with 29. Median water depth outside the building: 108 in.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 29 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 39.16 in |
| 12 months to August 2026 | 33.26 in (-5.90) |
| 2025 | 33.22 in (-5.94) |
| Wettest year since 1895 | 1973: 60.19 in |
| Driest year since 1895 | 1988: 21.07 in |
| Days with 1 inch or more, normal at DONNELLSON (19 mi away) | 10.4 |
Homes
| Housing units | 3,233 |
| Median year built | 1970 |
| Built before 1980 | 68% |
| Built 2000 or later | 14% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $130,700 |
| Single-family detached | 78% |
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 |
|---|---|---|---|
| Lee County, IA | 21 mi | 61% | 77% |
| Scotland County, MO | 22 mi | 70% | 76% |
| Lewis County, MO | 22 mi | 63% | 81% |
| Van Buren County, IA | 27 mi | 70% | 82% |
| Knox County, MO | 29 mi | 81% | 85% |
| Hancock County, IL | 30 mi | 48% | 72% |
| Adams County, IL | 41 mi | 36% | 70% |
| Henry County, IA | 41 mi | 76% | 86% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status