Cass County, Iowa
Shrink-swell clay limits houses without basements on 49% of Cass County's mapped land, a higher share than 90% of US counties. A shallow water table limits basements on 46%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 1 flood losses here since 2016. 79% 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 Cass County
| Expansive clay (limits slab homes) | 48.9% |
| High water table (limits basements) | 45.8% |
| Septic fields very limited | 96.9% |
| Clay swell (LEP, by area) | 5.3% |
| High-swell land (LEP 6%+) | 23.8% |
| Mapped soil | 361,700 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Marshall | 18% | 14% |
| Exira | 14% | n/a |
| Sharpsburg | 11% | 98% |
| Shelby | 10% | n/a |
| Judson | 9% | n/a |
| Colo | 6% | n/a |
How we count · survey areas IA029 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 5.3% by land area here, and 24% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 49% of the mapped land.
On 46% of Cass 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: 30.01 in, 5.90 in below the 1991-2020 average year of 35.91 in.
USDA rates 97% 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 5 of the last 52 weeks; the most was 100% of its area, in 2 weeks, most recently on the August 4, 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
1 flood losses since 2016, $2,271 paid. The worst year was 2016, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 35.91 in |
| 12 months to August 2026 | 30.01 in (-5.90) |
| 2025 | 30.81 in (-5.10) |
| Wettest year since 1895 | 1993: 49.83 in |
| Driest year since 1895 | 1988: 18.97 in |
| Days with 1 inch or more, normal at ATLANTIC 1 NE (7 mi away) | 9.5 |
Homes
| Housing units | 6,393 |
| Median year built | 1956 |
| Built before 1980 | 79% |
| Built 2000 or later | 9% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $150,300 |
| Single-family detached | 82% |
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 |
|---|---|---|---|
| Adair County, IA | 24 mi | 91% | 80% |
| Audubon County, IA | 24 mi | 30% | 29% |
| Montgomery County, IA | 25 mi | 36% | 40% |
| Adams County, IA | 25 mi | 88% | 78% |
| Shelby County, IA | 31 mi | 21% | 21% |
| Pottawattamie County, IA | 32 mi | 14% | 25% |
| Guthrie County, IA | 33 mi | 62% | 66% |
| Mills County, IA | 41 mi | 16% | 28% |
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