Ozaukee County, Wisconsin
A shallow water table limits basements on 43% of Ozaukee County's mapped land, a higher share than 60% of US counties. Shrink-swell clay limits houses without basements on 41%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 66 flood losses here since 2016, 71% of them in buildings with basements. 54% of homes were built before 1980, against 50% nationally; the median home dates from 1978.
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 Ozaukee County
| Expansive clay (limits slab homes) | 41.0% |
| High water table (limits basements) | 42.6% |
| Septic fields very limited | 88.0% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 31.2% |
| Mapped soil | 150,586 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Kewaunee | 29% | n/a |
| Ozaukee | 8% | over 99% |
| Manawa | 8% | n/a |
| Casco | 5% | n/a |
| Houghton | 3% | n/a |
| Poygan | 3% | n/a |
How we count · survey areas WI089 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 31% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 41% of the mapped land.
On 43% of Ozaukee 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: 31.71 in, 1.29 in below the 1991-2020 average year of 33.00 in.
USDA rates 88% 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 3 of the last 52 weeks; the most was 100% of its area, on the July 28, 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
66 flood losses since 2016, $1.5 million paid. The worst year was 2019, with 26. Foundations of the buildings, where recorded: 71% basements, 15% slabs, 10% crawl spaces, 4% elevated. Median water depth outside the building: 11 in.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 1 |
| 2018 | 8 |
| 2019 | 26 |
| 2020 | 2 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 22 |
| 2026 to date | 4 |
Rain
| Average year, 1991-2020 | 33.00 in |
| 12 months to August 2026 | 31.71 in (-1.29) |
| 2025 | 34.92 in (+1.92) |
| Wettest year since 1895 | 2008: 41.15 in |
| Driest year since 1895 | 1895: 20.15 in |
| Days with 1 inch or more, normal at PLYMOUTH WWTP (17 mi away) | 6.1 |
Homes
| Housing units | 39,872 |
| Median year built | 1978 |
| Built before 1980 | 54% |
| Built 2000 or later | 22% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $390,200 |
| Single-family detached | 66% |
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 |
|---|---|---|---|
| Sheboygan County, WI | 17 mi | 33% | 37% |
| Washington County, WI | 21 mi | 1% | 44% |
| Fond du Lac County, WI | 37 mi | 13% | 50% |
| Waukesha County, WI | 40 mi | 3% | 42% |
| Milwaukee County, WI | 41 mi | 8% | 57% |
| Dodge County, WI | 43 mi | 7% | 59% |
| Calumet County, WI | 44 mi | 44% | 42% |
| Manitowoc County, WI | 47 mi | 38% | 47% |
Sources: USDA SSURGO (September 10, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status