O'Brien County, Iowa
A shallow water table limits basements on 64% of O'Brien County's mapped land, a higher share than 77% of US counties. Shrink-swell clay limits houses without basements on 47%.
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. 74% 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 O'Brien County
| Expansive clay (limits slab homes) | 47.2% |
| High water table (limits basements) | 64.0% |
| Septic fields very limited | 98.9% |
| Clay swell (LEP, by area) | 5.5% |
| High-swell land (LEP 6%+) | 30.1% |
| Mapped soil | 367,100 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Galva | 32% | n/a |
| Primghar | 27% | n/a |
| Marcus | 12% | n/a |
| Sac | 10% | n/a |
| Colo | 3% | n/a |
| Afton | 3% | n/a |
How we count · survey areas IA141 (2025-09-09)
What the numbers mean here
Clay swell averages a linear extensibility of 5.5% by land area here, and 30% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 47% of the mapped land.
On 64% of O'Brien 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: 23.14 in, 7.60 in below the 1991-2020 average year of 30.74 in.
USDA rates 99% 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 24 of the last 52 weeks; the most was 100% of its area, in 7 weeks, most recently on the April 7, 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
3 flood losses since 2016, $143,375 paid. The worst year was 2018, with 2.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 2 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 30.74 in |
| 12 months to August 2026 | 23.14 in (-7.60) |
| 2025 | 31.18 in (+0.44) |
| Wettest year since 1895 | 2018: 47.44 in |
| Driest year since 1895 | 1958: 14.74 in |
| Days with 1 inch or more, normal at PRIMGHAR (0 mi away) | 7.5 |
Homes
| Housing units | 6,564 |
| Median year built | 1959 |
| Built before 1980 | 74% |
| Built 2000 or later | 11% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $173,100 |
| Single-family detached | 83% |
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 |
|---|---|---|---|
| Osceola County, IA | 20 mi | 21% | 76% |
| Cherokee County, IA | 24 mi | 27% | 36% |
| Clay County, IA | 24 mi | 32% | 77% |
| Sioux County, IA | 28 mi | 26% | 35% |
| Dickinson County, IA | 30 mi | 10% | 75% |
| Buena Vista County, IA | 34 mi | 22% | 83% |
| Lyon County, IA | 36 mi | 18% | 37% |
| Plymouth County, IA | 38 mi | 8% | 27% |
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