Jasper County, Iowa
A shallow water table limits basements on 55% of Jasper County's mapped land, a higher share than 71% of US counties. Shrink-swell clay limits houses without basements on 40%.
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. 73% of homes were built before 1980, against 50% nationally; the median home dates from 1965.
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 Jasper County
| Expansive clay (limits slab homes) | 40.3% |
| High water table (limits basements) | 54.9% |
| Septic fields very limited | 96.2% |
| Clay swell (LEP, by area) | 5.0% |
| High-swell land (LEP 6%+) | 20.0% |
| Mapped soil | 468,700 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Tama | 17% | 0% |
| Downs | 7% | n/a |
| Colo | 7% | n/a |
| Otley | 7% | n/a |
| Ackmore | 6% | n/a |
| Killduff | 6% | n/a |
How we count · survey areas IA099 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 5.0% by land area here, and 20% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 40% of the mapped land.
On 55% of Jasper 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: 37.76 in, 1.52 in above the 1991-2020 average year of 36.24 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. No part of the county was in drought in the last 52 weeks.
| 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
11 flood losses since 2016, $667,600 paid. The worst year was 2024, with 6.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 3 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 6 |
| 2025 | 1 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 36.24 in |
| 12 months to August 2026 | 37.76 in (+1.52) |
| 2025 | 35.61 in (-0.63) |
| Wettest year since 1895 | 2010: 54.60 in |
| Driest year since 1895 | 1988: 18.39 in |
| Days with 1 inch or more, normal at NEWTON (2 mi away) | 8.8 |
Homes
| Housing units | 16,249 |
| Median year built | 1965 |
| Built before 1980 | 73% |
| Built 2000 or later | 12% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $186,300 |
| 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 |
|---|---|---|---|
| Marion County, IA | 25 mi | 71% | 77% |
| Marshall County, IA | 25 mi | 42% | 47% |
| Polk County, IA | 27 mi | 13% | 52% |
| Poweshiek County, IA | 27 mi | 53% | 62% |
| Story County, IA | 32 mi | 9% | 64% |
| Mahaska County, IA | 33 mi | 71% | 88% |
| Warren County, IA | 36 mi | 81% | 80% |
| Tama County, IA | 38 mi | 42% | 49% |
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