Shawnee County, Kansas
Shrink-swell clay limits houses without basements on 65% of Shawnee County's mapped land, a higher share than 95% of US counties. A shallow water table limits basements on 59%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 69 flood losses here since 2016, 73% of them in buildings with basements. 63% of homes were built before 1980, against 50% nationally; the median home dates from 1972.
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 Shawnee County
| Expansive clay (limits slab homes) | 64.6% |
| High water table (limits basements) | 59.0% |
| Septic fields very limited | 91.9% |
| Clay swell (LEP, by area) | 6.9% |
| High-swell land (LEP 6%+) | 59.7% |
| Mapped soil | 355,488 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Martin | 22% | n/a |
| Pawnee | 13% | n/a |
| Ladysmith | 9% | n/a |
| Vinland | 5% | n/a |
| Sogn | 5% | n/a |
| Reading | 4% | n/a |
How we count · survey areas KS177 (2025-08-26)
What the numbers mean here
Clay swell averages a linear extensibility of 6.9% by land area here, and 60% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 65% of the mapped land.
On 59% of Shawnee 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: 34.73 in, 1.70 in below the 1991-2020 average year of 36.43 in.
USDA rates 92% 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 12 of the last 52 weeks; the most was 40.1% of its area, on the November 18, 2025 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
69 flood losses since 2016, $707,353 paid. The worst year was 2020, with 23. Foundations of the buildings, where recorded: 73% basements, 6% slabs, 6% crawl spaces, 15% elevated. Median water depth outside the building: 5 in.
| Year | Flood losses |
|---|---|
| 2016 | 11 |
| 2017 | 3 |
| 2018 | 0 |
| 2019 | 8 |
| 2020 | 23 |
| 2021 | 3 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 1 |
| 2025 | 1 |
| 2026 to date | 18 |
Rain
| Average year, 1991-2020 | 36.43 in |
| 12 months to August 2026 | 34.73 in (-1.70) |
| 2025 | 30.93 in (-5.50) |
| Wettest year since 1895 | 1973: 57.02 in |
| Driest year since 1895 | 1988: 20.40 in |
| Days with 1 inch or more, normal at TOPEKA MUNI AP (7 mi away) | 10.5 |
Homes
| Housing units | 81,075 |
| Median year built | 1972 |
| Built before 1980 | 63% |
| Built 2000 or later | 15% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $180,900 |
| Single-family detached | 71% |
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 |
|---|---|---|---|
| Jefferson County, KS | 25 mi | 59% | 54% |
| Wabaunsee County, KS | 25 mi | 73% | 27% |
| Jackson County, KS | 26 mi | 76% | 73% |
| Douglas County, KS | 27 mi | 56% | 51% |
| Osage County, KS | 27 mi | 77% | 69% |
| Pottawatomie County, KS | 39 mi | 71% | 35% |
| Leavenworth County, KS | 40 mi | 63% | 52% |
| Atchison County, KS | 41 mi | 73% | 62% |
Sources: USDA SSURGO (August 26, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status