Whiteside County, Illinois
A shallow water table limits basements on 40% of Whiteside County's mapped land, a higher share than 58% of US counties. Shrink-swell clay limits houses without basements on 2%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 48 flood losses here since 2016, 52% of them in buildings with basements. 78% of homes were built before 1980, against 50% nationally; the median home dates from 1961.
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 Whiteside County
| Expansive clay (limits slab homes) | 2.5% |
| High water table (limits basements) | 40.3% |
| Septic fields very limited | 71.3% |
| Clay swell (LEP, by area) | 3.0% |
| High-swell land (LEP 6%+) | 2.1% |
| Mapped soil | 446,170 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Seaton | 8% | n/a |
| Dickinson | 6% | n/a |
| Richwood | 4% | n/a |
| Greenbush | 4% | n/a |
| Ambraw | 4% | n/a |
| Marshan | 4% | n/a |
How we count · survey areas IL195 (2025-08-31)
What the numbers mean here
On 40% of Whiteside 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: 33.04 in, 5.35 in below the 1991-2020 average year of 38.39 in.
USDA rates 71% 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 19 of the last 52 weeks; the most was 100% of its area, in 16 weeks, most recently on the June 9, 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
48 flood losses since 2016, $369,426 paid. The worst year was 2019, with 28. Foundations of the buildings, where recorded: 52% basements, 15% slabs, 33% elevated. Median water depth outside the building: 10.5 in.
| Year | Flood losses |
|---|---|
| 2016 | 2 |
| 2017 | 1 |
| 2018 | 6 |
| 2019 | 28 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 9 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 38.39 in |
| 12 months to August 2026 | 33.04 in (-5.35) |
| 2025 | 30.84 in (-7.55) |
| Wettest year since 1895 | 2019: 52.39 in |
| Driest year since 1895 | 1910: 21.58 in |
| Days with 1 inch or more, normal at MORRISON (4 mi away) | 10.4 |
Homes
| Housing units | 25,837 |
| Median year built | 1961 |
| Built before 1980 | 78% |
| Built 2000 or later | 10% |
| Owner-occupied | 77% |
| Median value, owner-occupied | $127,100 |
| 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 |
|---|---|---|---|
| Carroll County, IL | 22 mi | 13% | 17% |
| Henry County, IL | 30 mi | 19% | 48% |
| Bureau County, IL | 31 mi | 25% | 53% |
| Lee County, IL | 32 mi | 14% | 66% |
| Clinton County, IA | 34 mi | 15% | 44% |
| Ogle County, IL | 36 mi | 10% | 35% |
| Scott County, IA | 37 mi | 36% | 41% |
| Rock Island County, IL | 39 mi | 6% | 32% |
Sources: USDA SSURGO (August 31, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status