Warren County, Iowa
Shrink-swell clay limits houses without basements on 81% of Warren County's mapped land, a higher share than 99% of US counties and the 6th highest of 99 Iowa counties. A shallow water table limits basements on 80%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 3 flood losses here since 2016. 46% of homes were built before 1980, against 50% nationally; the median home dates from 1985.
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 Warren County
| Expansive clay (limits slab homes) | 80.9% |
| High water table (limits basements) | 79.6% |
| Septic fields very limited | 96.8% |
| Clay swell (LEP, by area) | 6.6% |
| High-swell land (LEP 6%+) | 61.3% |
| Mapped soil | 366,900 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Sharpsburg | 12% | 98% |
| Ladoga | 8% | n/a |
| Gara | 7% | 65% |
| Zook | 6% | n/a |
| Colo | 5% | n/a |
| Munterville | 5% | n/a |
How we count · survey areas IA181 (2025-09-09)
What the numbers mean here
Clay swell averages a linear extensibility of 6.6% by land area here, and 61% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 81% of the mapped land.
On 80% of Warren 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: 37.68 in, 1.23 in above the 1991-2020 average year of 36.45 in.
USDA rates 97% 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. No part of the county was in drought in the last 52 weeks.
| 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
3 flood losses since 2016, $25,145 paid. The worst year was 2019, with 2.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 2 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 36.45 in |
| 12 months to August 2026 | 37.68 in (+1.23) |
| 2025 | 32.11 in (-4.34) |
| Wettest year since 1895 | 2010: 52.87 in |
| Driest year since 1895 | 1910: 18.70 in |
| Days with 1 inch or more, normal at INDIANOLA 2W (5 mi away) | 9.5 |
Homes
| Housing units | 21,921 |
| Median year built | 1985 |
| Built before 1980 | 46% |
| Built 2000 or later | 36% |
| Owner-occupied | 82% |
| Median value, owner-occupied | $269,600 |
| Single-family detached | 77% |
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 |
|---|---|---|---|
| Madison County, IA | 23 mi | 88% | 77% |
| Clarke County, IA | 24 mi | 74% | 78% |
| Lucas County, IA | 24 mi | 73% | 78% |
| Polk County, IA | 24 mi | 13% | 52% |
| Marion County, IA | 25 mi | 71% | 77% |
| Dallas County, IA | 34 mi | 17% | 60% |
| Jasper County, IA | 36 mi | 40% | 55% |
| Union County, IA | 41 mi | 85% | 78% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status