Lake County, Illinois
A shallow water table limits basements on 87% of Lake County's mapped land, a higher share than 94% of US counties. Shrink-swell clay limits houses without basements on 16%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 655 flood losses here since 2016, 40% of them in buildings with basements. 46% of homes were built before 1980, against 50% nationally; the median home dates from 1983.
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 Lake County
| Expansive clay (limits slab homes) | 15.9% |
| High water table (limits basements) | 86.7% |
| Septic fields very limited | 91.6% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 14.7% |
| Urban land, not rated | 1.0% |
| Mapped soil | 301,435 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Ozaukee | 21% | over 99% |
| Markham | 7% | n/a |
| Ashkum | 7% | n/a |
| Houghton | 6% | n/a |
| Pella | 5% | n/a |
| Beecher | 4% | n/a |
How we count · survey areas IL097 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 15% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 16% of the mapped land.
On 87% of Lake 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: 39.05 in, 2.22 in above the 1991-2020 average year of 36.83 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 8 of the last 52 weeks; the most was 100% of its area, in 2 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
655 flood losses since 2016, $13.6 million paid. The worst year was 2017, with 428. Foundations of the buildings, where recorded: 40% basements, 15% slabs, 33% crawl spaces, 12% elevated. Median water depth outside the building: 11 in.
| Year | Flood losses |
|---|---|
| 2016 | 4 |
| 2017 | 428 |
| 2018 | 19 |
| 2019 | 59 |
| 2020 | 60 |
| 2021 | 1 |
| 2022 | 10 |
| 2023 | 4 |
| 2024 | 11 |
| 2025 | 0 |
| 2026 to date | 59 |
Rain
| Average year, 1991-2020 | 36.83 in |
| 12 months to August 2026 | 39.05 in (+2.22) |
| 2025 | 28.44 in (-8.39) |
| Wettest year since 1895 | 2019: 50.44 in |
| Driest year since 1895 | 1901: 19.90 in |
| Days with 1 inch or more, normal at CHICAGO BOTANIC GARDEN (3 mi away) | 8.3 |
Homes
| Housing units | 270,618 |
| Median year built | 1983 |
| Built before 1980 | 46% |
| Built 2000 or later | 21% |
| Owner-occupied | 75% |
| Median value, owner-occupied | $345,700 |
| Single-family detached | 67% |
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 |
|---|---|---|---|
| Cook County, IL | 22 mi | 25% | 59% |
| DuPage County, IL | 27 mi | 33% | 90% |
| Kenosha County, WI | 28 mi | 15% | 76% |
| McHenry County, IL | 34 mi | 2% | 54% |
| Kane County, IL | 36 mi | 8% | 82% |
| Racine County, WI | 41 mi | 15% | 76% |
| Walworth County, WI | 50 mi | under 1% | 33% |
| Milwaukee County, WI | 50 mi | 8% | 57% |
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