Ontonagon County, Michigan
A shallow water table limits basements on 78% of Ontonagon County's mapped land, a higher share than 87% of US counties. Shrink-swell clay limits houses without basements on 22%.
98.8% of the county is in drought on the October 13, 2026 Drought Monitor map, up from 84.1% a week earlier. FEMA's flood data list 1 flood losses here since 2016. 71% of homes were built before 1980, against 50% nationally; the median home dates from 1963.
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 Ontonagon County
| Expansive clay (limits slab homes) | 22.5% |
| High water table (limits basements) | 78.0% |
| Septic fields very limited | 96.3% |
| Clay swell (LEP, by area) | 3.5% |
| High-swell land (LEP 6%+) | 24.1% |
| Mapped soil | 848,723 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Gogebic | 8% | n/a |
| Flintsteel | 8% | n/a |
| Big Iron | 7% | n/a |
| Loggerhead | 5% | n/a |
| Amnicon | 5% | n/a |
| Cuttre | 4% | n/a |
How we count · survey areas MI131 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 3.5% by land area here, and 24% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 22% of the mapped land.
Clay shrinks as it dries: 98.8% of the county is in drought on the latest map, and 22% of Ontonagon County's mapped land has shrink-swell clay.
On 78% of Ontonagon 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: 32.46 in, 1.02 in below the 1991-2020 average year of 33.48 in.
USDA rates 96% of the land very limited for septic absorption fields.
Drought
98.8% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 14 of the last 52 weeks; the most was 98.8% of its area, on the October 13, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 98.8% |
| D2 severe or worse | 72.8% |
| D3 extreme or worse | 38.3% |
| D4 exceptional | 0% |
Flood losses since 2016
1 flood losses since 2016, $0 paid. The worst year was 2021, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 33.48 in |
| 12 months to August 2026 | 32.46 in (-1.02) |
| 2025 | 37.19 in (+3.71) |
| Wettest year since 1895 | 1951: 41.90 in |
| Driest year since 1895 | 1910: 19.83 in |
| Days with 1 inch or more, normal at BERGLAND DAM (21 mi away) | 6.2 |
Homes
| Housing units | 5,238 |
| Median year built | 1963 |
| Built before 1980 | 71% |
| Built 2000 or later | 11% |
| Owner-occupied | 87% |
| Median value, owner-occupied | $111,700 |
| Single-family detached | 90% |
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 |
|---|---|---|---|
| Houghton County, MI | 32 mi | 2% | 66% |
| Gogebic County, MI | 34 mi | 1% | 84% |
| Baraga County, MI | 44 mi | 1% | 53% |
| Vilas County, WI | 55 mi | 0% | 36% |
| Keweenaw County, MI | 57 mi | 0% | 31% |
| Iron County, MI | 57 mi | 0% | 57% |
| Iron County, WI | 58 mi | 1% | 75% |
| Ashland County, WI | 69 mi | 18% | 76% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status