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Brown County, Illinois

A shallow water table limits basements on 38% of Brown County's mapped land, a higher share than 57% of US counties. Shrink-swell clay limits houses without basements on 29%.

None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 1 flood losses here since 2016. 74% of homes were built before 1980, against 50% nationally; the median home dates from 1960.

Data as of October 13, 2026 · sources

29%

expansive clay: shrink-swell limits slab homes

38%

high water table: limits basements

0%

in drought, October 13, 2026

74%

of homes built before 1980

Soil under Brown County

Expansive clay (limits slab homes)28.7%
High water table (limits basements)37.9%
Septic fields very limited68.3%
Clay swell (LEP, by area)4.3%
High-swell land (LEP 6%+)26.3%
Mapped soil197,030 acres
Soil seriesShare hereSeries nationally: high water table
Hickory15%n/a
Rozetta13%n/a
Fayette11%0%
Keomah9%n/a
Marseilles7%n/a
Seaton4%n/a
Schuyler County: 46%Adams County: 70%Pike County: 56%Scott County: 47%Cass County: 45%Morgan County: 54%McDonough County: 70%Hancock County: 72%Brown County SchuylerAdamsPikeScottCassMorganMcDonoughHancockBrown
Brown County (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas IL009 (2025-08-31)

What the numbers mean here

Clay swell averages a linear extensibility of 4.3% by land area here, and 26% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 29% of the mapped land.

On 38% of Brown 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: 35.18 in, 3.42 in below the 1991-2020 average year of 38.60 in.

USDA rates 68% 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 24 of the last 52 weeks; the most was 100% of its area, in 21 weeks, most recently on the March 10, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse0%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

1 flood losses since 2016, $1,623 paid. The worst year was 2016, with 1.

YearFlood losses
20161
20170
20180
20190
20200
20210
20220
20230
20240
20250
2026 to date0

Rain

Average year, 1991-202038.60 in
12 months to August 202635.18 in (-3.42)
202529.55 in (-9.05)
Wettest year since 18951973: 55.54 in
Driest year since 18951953: 21.78 in
Days with 1 inch or more, normal at RUSHVILLE (15 mi away)11.1

Homes

Housing units2,321
Median year built1960
Built before 198074%
Built 2000 or later12%
Owner-occupied72%
Median value, owner-occupied$150,300
Single-family detached81%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Basement waterproofing, US $3,000 to $10,000 Fixr, February 6, 2026
Sump pump installation, US $800 to $2,000 Fixr, January 31, 2025
Crawl space encapsulation, US $2,000 to $8,000 Fixr, August 29, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Schuyler County, IL 15 mi 31% 46%
Adams County, IL 24 mi 36% 70%
Pike County, IL 24 mi 9% 56%
Scott County, IL 27 mi 27% 47%
Cass County, IL 27 mi 13% 45%
Morgan County, IL 33 mi 43% 54%
McDonough County, IL 34 mi 63% 70%
Hancock County, IL 38 mi 48% 72%

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