Mills County, Iowa
A shallow water table limits basements on 28% of Mills County's mapped land. Shrink-swell clay limits houses without basements on 16%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 32 flood losses here since 2016. 61% of homes were built before 1980, against 50% nationally; the median home dates from 1972.
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 Mills County
| Expansive clay (limits slab homes) | 16.0% |
| High water table (limits basements) | 27.7% |
| Septic fields very limited | 71.2% |
| Clay swell (LEP, by area) | 4.2% |
| High-swell land (LEP 6%+) | 10.5% |
| Mapped soil | 281,900 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Marshall | 17% | 0% |
| Monona | 15% | n/a |
| Napier | 9% | n/a |
| Ida | 8% | n/a |
| Exira | 8% | n/a |
| Judson | 6% | n/a |
How we count · survey areas IA129 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 4.2% by land area here, and 11% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 16% of the mapped land.
On 28% of Mills 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: 30.46 in, 3.66 in below the 1991-2020 average year of 34.12 in.
USDA rates 71% 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 1 of the last 52 weeks; the most was 6.5% of its area, 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
32 flood losses since 2016, $5.5 million paid. The worst year was 2019, with 31. Median water depth outside the building: 95 in.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 31 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 34.12 in |
| 12 months to August 2026 | 30.46 in (-3.66) |
| 2025 | 26.92 in (-7.20) |
| Wettest year since 1895 | 1993: 51.53 in |
| Driest year since 1895 | 1934: 18.69 in |
| Days with 1 inch or more, normal at RANDOLPH (11 mi away) | 9.4 |
Homes
| Housing units | 6,134 |
| Median year built | 1972 |
| Built before 1980 | 61% |
| Built 2000 or later | 20% |
| Owner-occupied | 84% |
| Median value, owner-occupied | $237,800 |
| Single-family detached | 84% |
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 |
|---|---|---|---|
| Fremont County, IA | 20 mi | 22% | 39% |
| Pottawattamie County, IA | 21 mi | 14% | 25% |
| Montgomery County, IA | 24 mi | 36% | 40% |
| Sarpy County, NE | 26 mi | 7% | 15% |
| Cass County, NE | 29 mi | 71% | 21% |
| Page County, IA | 32 mi | 63% | 63% |
| Douglas County, NE | 33 mi | 3% | 19% |
| Otoe County, NE | 38 mi | 71% | 65% |
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