Monona County, Iowa
A shallow water table limits basements on 46% of Monona County's mapped land, a higher share than 63% of US counties. Shrink-swell clay limits houses without basements on 30%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 11 flood losses here since 2016. 74% of homes were built before 1980, against 50% nationally; the median home dates from 1956.
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 Monona County
| Expansive clay (limits slab homes) | 30.2% |
| High water table (limits basements) | 46.1% |
| Septic fields very limited | 68.8% |
| Clay swell (LEP, by area) | 4.9% |
| High-swell land (LEP 6%+) | 35.8% |
| Mapped soil | 447,300 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Ida | 16% | n/a |
| Napier | 14% | n/a |
| Luton | 13% | n/a |
| Monona | 12% | n/a |
| Albaton | 5% | n/a |
| Onawa | 3% | n/a |
How we count · survey areas IA133 (2025-09-09)
What the numbers mean here
Clay swell averages a linear extensibility of 4.9% by land area here, and 36% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 30% of the mapped land.
On 46% of Monona 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: 24.20 in, 6.71 in below the 1991-2020 average year of 30.91 in.
USDA rates 69% 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 2 weeks, most recently on the August 11, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0.8% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
11 flood losses since 2016, $217,364 paid. The worst year was 2024, with 6.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 5 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 6 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 30.91 in |
| 12 months to August 2026 | 24.20 in (-6.71) |
| 2025 | 32.83 in (+1.92) |
| Wettest year since 1895 | 1903: 43.53 in |
| Driest year since 1895 | 1976: 14.76 in |
| Days with 1 inch or more, normal at CASTANA EXP FARM (6 mi away) | 7.4 |
Homes
| Housing units | 4,372 |
| Median year built | 1956 |
| Built before 1980 | 74% |
| Built 2000 or later | 11% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $142,900 |
| Single-family detached | 85% |
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 |
|---|---|---|---|
| Burt County, NE | 24 mi | 32% | 30% |
| Woodbury County, IA | 24 mi | 16% | 25% |
| Harrison County, IA | 26 mi | 17% | 30% |
| Crawford County, IA | 29 mi | 12% | 15% |
| Thurston County, NE | 30 mi | 4% | 14% |
| Ida County, IA | 33 mi | 23% | 27% |
| Washington County, NE | 38 mi | 20% | 16% |
| Dakota County, NE | 39 mi | 13% | 22% |
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