Lyon County, Iowa
A shallow water table limits basements on 37% of Lyon County's mapped land, a higher share than 55% of US counties. Shrink-swell clay limits houses without basements on 18%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 13 flood losses here since 2016. 65% of homes were built before 1980, against 50% nationally; the median home dates from 1967.
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 Lyon County
| Expansive clay (limits slab homes) | 18.4% |
| High water table (limits basements) | 36.7% |
| Septic fields very limited | 95.0% |
| Clay swell (LEP, by area) | 4.8% |
| High-swell land (LEP 6%+) | 11.2% |
| Mapped soil | 376,200 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Moody | 27% | 0% |
| Galva | 18% | n/a |
| Primghar | 8% | n/a |
| Trent | 5% | n/a |
| Egan | 4% | n/a |
| Calco | 3% | n/a |
How we count · survey areas IA119 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 4.8% by land area here, and 11% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 18% of the mapped land.
On 37% of Lyon 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: 20.62 in, 8.52 in below the 1991-2020 average year of 29.14 in.
USDA rates 95% 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 50 of the last 52 weeks; the most was 100% of its area, in 9 weeks, most recently on the April 21, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 2.3% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
13 flood losses since 2016, $421,431 paid. The worst year was 2024, with 13.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 13 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 29.14 in |
| 12 months to August 2026 | 20.62 in (-8.52) |
| 2025 | 25.96 in (-3.18) |
| Wettest year since 1895 | 2018: 46.52 in |
| Driest year since 1895 | 1976: 14.11 in |
| Days with 1 inch or more, normal at ROCK RAPIDS (4 mi away) | 6.4 |
Homes
| Housing units | 4,870 |
| Median year built | 1967 |
| Built before 1980 | 65% |
| Built 2000 or later | 18% |
| Owner-occupied | 81% |
| Median value, owner-occupied | $230,000 |
| Single-family detached | 89% |
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 |
|---|---|---|---|
| Rock County, MN | 20 mi | 24% | 54% |
| Sioux County, IA | 21 mi | 26% | 35% |
| Lincoln County, SD | 27 mi | 28% | 51% |
| Osceola County, IA | 29 mi | 21% | 76% |
| Nobles County, MN | 30 mi | 10% | 90% |
| Minnehaha County, SD | 35 mi | 17% | 32% |
| O'Brien County, IA | 36 mi | 47% | 64% |
| Pipestone County, MN | 44 mi | 8% | 75% |
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