Sullivan County, Indiana
A shallow water table limits basements on 61% of Sullivan County's mapped land, a higher share than 75% 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 no flood losses here since 2016. 58% of homes were built before 1980, against 50% nationally; the median home dates from 1973.
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 Sullivan County
| Expansive clay (limits slab homes) | 2.1% |
| High water table (limits basements) | 61.1% |
| Septic fields very limited | 89.8% |
| Clay swell (LEP, by area) | 3.2% |
| High-swell land (LEP 6%+) | 1.3% |
| Mapped soil | 290,343 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Reesville | 16% | n/a |
| Iva | 5% | n/a |
| Iona | 5% | n/a |
| Ava | 5% | n/a |
| Alford | 5% | n/a |
| Stendal | 4% | n/a |
How we count · survey areas IN153 (2025-09-03)
What the numbers mean here
On 61% of Sullivan 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: 41.67 in, 3.81 in below the 1991-2020 average year of 45.48 in.
USDA rates 90% 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 20 of the last 52 weeks; the most was 50.8% of its area, in 2 weeks, most recently on the March 3, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 90.7% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Sullivan County since 2016.
Rain
| Average year, 1991-2020 | 45.48 in |
| 12 months to August 2026 | 41.67 in (-3.81) |
| 2025 | 44.33 in (-1.15) |
| Wettest year since 1895 | 1945: 59.23 in |
| Driest year since 1895 | 1953: 27.64 in |
| Days with 1 inch or more, normal at FARMERSBURG TV-2 (11 mi away) | 11.8 |
Homes
| Housing units | 8,791 |
| Median year built | 1973 |
| Built before 1980 | 58% |
| Built 2000 or later | 20% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $131,100 |
| Single-family detached | 77% |
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 |
|---|---|---|---|
| Crawford County, IL | 20 mi | 43% | 81% |
| Greene County, IN | 22 mi | 9% | 52% |
| Vigo County, IN | 24 mi | 1% | 58% |
| Clark County, IL | 26 mi | 29% | 77% |
| Clay County, IN | 26 mi | 2% | 69% |
| Knox County, IN | 28 mi | 8% | 46% |
| Lawrence County, IL | 31 mi | 23% | 78% |
| Daviess County, IN | 33 mi | 5% | 64% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status