Clarke County, Iowa
A shallow water table limits basements on 78% of Clarke County's mapped land, a higher share than 87% of US counties. Shrink-swell clay limits houses without basements on 74%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 63% of homes were built before 1980, against 50% nationally; the median home dates from 1975.
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 Clarke County
| Expansive clay (limits slab homes) | 74.4% |
| High water table (limits basements) | 78.1% |
| Septic fields very limited | 98.2% |
| Clay swell (LEP, by area) | 6.9% |
| High-swell land (LEP 6%+) | 64.3% |
| Mapped soil | 276,000 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Gara | 10% | 5% |
| Arispe | 10% | n/a |
| Lamoni | 9% | n/a |
| Shelby | 8% | n/a |
| Grundy | 7% | n/a |
| Clarinda | 7% | n/a |
How we count · survey areas IA039 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 6.9% by land area here, and 64% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 74% of the mapped land.
On 78% of Clarke 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: 37.29 in, 0.05 in above the 1991-2020 average year of 37.24 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 5 of the last 52 weeks; the most was 45.8% of its area, in 5 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
FEMA's flood data list no flood losses in Clarke County since 2016.
Rain
| Average year, 1991-2020 | 37.24 in |
| 12 months to August 2026 | 37.29 in (+0.05) |
| 2025 | 33.74 in (-3.50) |
| Wettest year since 1895 | 1993: 52.93 in |
| Driest year since 1895 | 1988: 17.58 in |
| Days with 1 inch or more, normal at OSCEOLA (2 mi away) | 9.3 |
Homes
| Housing units | 4,522 |
| Median year built | 1975 |
| Built before 1980 | 63% |
| Built 2000 or later | 21% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $161,100 |
| Single-family detached | 71% |
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 |
|---|---|---|---|
| Decatur County, IA | 20 mi | 66% | 76% |
| Lucas County, IA | 24 mi | 73% | 78% |
| Warren County, IA | 24 mi | 81% | 80% |
| Union County, IA | 24 mi | 85% | 78% |
| Madison County, IA | 24 mi | 88% | 77% |
| Wayne County, IA | 31 mi | 77% | 80% |
| Ringgold County, IA | 31 mi | 76% | 77% |
| Adair County, IA | 42 mi | 91% | 80% |
Sources: USDA SSURGO (September 8, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status