Poweshiek County, Iowa
A shallow water table limits basements on 62% of Poweshiek County's mapped land, a higher share than 75% of US counties. Shrink-swell clay limits houses without basements on 53%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 65% of homes were built before 1980, against 50% nationally; the median home dates from 1971.
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 Poweshiek County
| Expansive clay (limits slab homes) | 52.7% |
| High water table (limits basements) | 61.6% |
| Septic fields very limited | 99.2% |
| Clay swell (LEP, by area) | 5.5% |
| High-swell land (LEP 6%+) | 31.0% |
| Mapped soil | 374,900 acres |
How we count · survey areas IA157 (2025-09-09)
What the numbers mean here
Clay swell averages a linear extensibility of 5.5% by land area here, and 31% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 53% of the mapped land.
On 62% of Poweshiek 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: 36.27 in, 1.15 in below the 1991-2020 average year of 37.42 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 7 of the last 52 weeks; the most was 32.3% of its area, in 6 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
FEMA's flood data list no flood losses in Poweshiek County since 2016.
Rain
| Average year, 1991-2020 | 37.42 in |
| 12 months to August 2026 | 36.27 in (-1.15) |
| 2025 | 34.87 in (-2.55) |
| Wettest year since 1895 | 1993: 55.12 in |
| Driest year since 1895 | 1988: 17.83 in |
| Days with 1 inch or more, normal at BROOKLYN (6 mi away) | 10 |
Homes
| Housing units | 8,975 |
| Median year built | 1971 |
| Built before 1980 | 65% |
| Built 2000 or later | 18% |
| Owner-occupied | 71% |
| Median value, owner-occupied | $209,300 |
| 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 |
|---|---|---|---|
| Iowa County, IA | 24 mi | 57% | 69% |
| Mahaska County, IA | 25 mi | 71% | 88% |
| Tama County, IA | 27 mi | 42% | 49% |
| Jasper County, IA | 27 mi | 40% | 55% |
| Keokuk County, IA | 31 mi | 71% | 87% |
| Marshall County, IA | 34 mi | 42% | 47% |
| Benton County, IA | 37 mi | 33% | 73% |
| Marion County, IA | 38 mi | 71% | 77% |
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