Des Moines County, Iowa
A shallow water table limits basements on 80% of Des Moines County's mapped land, a higher share than 89% of US counties. Shrink-swell clay limits houses without basements on 57%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 108 flood losses here since 2016, 7% of them in buildings with basements. 75% of homes were built before 1980, against 50% nationally; the median home dates from 1959.
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 Des Moines County
| Expansive clay (limits slab homes) | 57.2% |
| High water table (limits basements) | 80.3% |
| Septic fields very limited | 95.5% |
| Clay swell (LEP, by area) | 6.1% |
| High-swell land (LEP 6%+) | 55.9% |
| Mapped soil | 274,500 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Clinton | 14% | n/a |
| Taintor | 11% | n/a |
| Mahaska | 11% | n/a |
| Lindley | 11% | n/a |
| Givin | 4% | n/a |
| Keomah | 3% | n/a |
How we count · survey areas IA057 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 6.1% by land area here, and 56% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 57% of the mapped land.
On 80% of Des Moines 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: 36.87 in, 1.30 in below the 1991-2020 average year of 38.17 in.
USDA rates 96% 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 19 of the last 52 weeks; the most was 100% of its area, in 16 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
108 flood losses since 2016, $2.3 million paid. The worst year was 2019, with 35. Foundations of the buildings, where recorded: 7% basements, 82% slabs, 1% crawl spaces, 9% elevated. Median water depth outside the building: 32 in.
| Year | Flood losses |
|---|---|
| 2016 | 9 |
| 2017 | 14 |
| 2018 | 21 |
| 2019 | 35 |
| 2020 | 5 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 8 |
| 2024 | 12 |
| 2025 | 0 |
| 2026 to date | 4 |
Rain
| Average year, 1991-2020 | 38.17 in |
| 12 months to August 2026 | 36.87 in (-1.30) |
| 2025 | 31.69 in (-6.48) |
| Wettest year since 1895 | 2009: 54.01 in |
| Driest year since 1895 | 1901: 20.66 in |
| Days with 1 inch or more, normal at GLADSTONE DAM 18 (9 mi away) | 9.5 |
Homes
| Housing units | 18,802 |
| Median year built | 1959 |
| Built before 1980 | 75% |
| Built 2000 or later | 11% |
| Owner-occupied | 75% |
| Median value, owner-occupied | $136,500 |
| Single-family detached | 79% |
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 |
|---|---|---|---|
| Henderson County, IL | 15 mi | 13% | 43% |
| Henry County, IA | 19 mi | 76% | 86% |
| Louisa County, IA | 21 mi | 38% | 70% |
| Lee County, IA | 24 mi | 61% | 77% |
| Warren County, IL | 30 mi | 35% | 54% |
| Mercer County, IL | 31 mi | 15% | 44% |
| Hancock County, IL | 36 mi | 48% | 72% |
| Muscatine County, IA | 39 mi | 20% | 50% |
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