Mahnomen County, Minnesota
A shallow water table limits basements on 69% of Mahnomen County's mapped land, a higher share than 81% of US counties. Shrink-swell clay limits houses without basements on 13%.
90.4% 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. 58% of homes were built before 1980, against 50% nationally; the median home dates from 1975.
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 Mahnomen County
| Expansive clay (limits slab homes) | 13.0% |
| High water table (limits basements) | 68.6% |
| Septic fields very limited | 81.2% |
| Clay swell (LEP, by area) | 3.8% |
| High-swell land (LEP 6%+) | 13.0% |
| Mapped soil | 373,300 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Vallers | 10% | n/a |
| Hamerly | 8% | n/a |
| Naytahwaush | 8% | n/a |
| Waukon | 6% | n/a |
| Hokans | 5% | n/a |
| Sugarbush | 4% | n/a |
How we count · survey areas MN087 (2025-09-10)
What the numbers mean here
On 69% of Mahnomen 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: 18.88 in, 6.36 in below the 1991-2020 average year of 25.24 in.
USDA rates 81% of the land very limited for septic absorption fields.
Drought
90.4% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 43 of the last 52 weeks; the most was 100% of its area, in 9 weeks, most recently on the September 22, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 90.4% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
1 flood losses since 2016, $0 paid. The worst year was 2023, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 25.24 in |
| 12 months to August 2026 | 18.88 in (-6.36) |
| 2025 | 23.82 in (-1.42) |
| Wettest year since 1895 | 2010: 32.47 in |
| Driest year since 1895 | 1936: 12.55 in |
| Days with 1 inch or more, normal at ITASCA UNIV OF MINN (30 mi away) | 5 |
Homes
| Housing units | 2,547 |
| Median year built | 1975 |
| Built before 1980 | 58% |
| Built 2000 or later | 19% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $161,900 |
| Single-family detached | 80% |
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 |
|---|---|---|---|
| Clearwater County, MN | 27 mi | 9% | 60% |
| Becker County, MN | 27 mi | 4% | 44% |
| Norman County, MN | 31 mi | 27% | 93% |
| Red Lake County, MN | 39 mi | 11% | 98% |
| Polk County, MN | 41 mi | 10% | 85% |
| Clay County, MN | 44 mi | 17% | 84% |
| Hubbard County, MN | 45 mi | 0% | 26% |
| Pennington County, MN | 52 mi | 5% | 98% |
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