Calhoun County, Illinois
A shallow water table limits basements on 25% of Calhoun County's mapped land. Shrink-swell clay limits houses without basements on 4%.
86.8% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 102 flood losses here since 2016, 33% of them in buildings with basements. 62% of homes were built before 1980, against 50% nationally; the median home dates from 1968.
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 Calhoun County
| Expansive clay (limits slab homes) | 3.7% |
| High water table (limits basements) | 24.9% |
| Septic fields very limited | 63.0% |
| Clay swell (LEP, by area) | 3.4% |
| High-swell land (LEP 6%+) | 2.6% |
| Mapped soil | 181,505 acres |
How we count · survey areas IL013 (2025-09-01)
What the numbers mean here
On 25% of Calhoun 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: 30.77 in, 9.52 in below the 1991-2020 average year of 40.29 in.
USDA rates 63% of the land very limited for septic absorption fields.
Drought
86.8% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 25 of the last 52 weeks; the most was 100% of its area, in 13 weeks, most recently on the March 3, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 86.8% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
102 flood losses since 2016, $2.5 million paid. The worst year was 2019, with 87. Foundations of the buildings, where recorded: 33% basements, 23% slabs, 2% crawl spaces, 42% elevated. Median water depth outside the building: 37 in.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 8 |
| 2018 | 2 |
| 2019 | 87 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 3 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 40.29 in |
| 12 months to August 2026 | 30.77 in (-9.52) |
| 2025 | 30.50 in (-9.79) |
| Wettest year since 1895 | 1993: 56.76 in |
| Driest year since 1895 | 1901: 23.69 in |
| Days with 1 inch or more, normal at ELSBERRY 1 S (6 mi away) | 10 |
Homes
| Housing units | 2,300 |
| Median year built | 1968 |
| Built before 1980 | 62% |
| Built 2000 or later | 16% |
| Owner-occupied | 89% |
| Median value, owner-occupied | $190,900 |
| Single-family detached | 83% |
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 |
|---|---|---|---|
| Jersey County, IL | 17 mi | 22% | 53% |
| Lincoln County, MO | 17 mi | 64% | 55% |
| Greene County, IL | 20 mi | 20% | 51% |
| St. Charles County, MO | 26 mi | 41% | 62% |
| Pike County, MO | 30 mi | 45% | 69% |
| Pike County, IL | 34 mi | 9% | 56% |
| Scott County, IL | 34 mi | 27% | 47% |
| St. Louis County, MO | 38 mi | 5% | 37% |
Sources: USDA SSURGO (September 1, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status