Idaho County, Idaho
USDA's soil survey flags shrink-swell clay on 9% of Idaho County's mapped land and a shallow water table under basements on 12%, both below the national shares of 15% and 29%. The soil survey maps 41% of the county's land area; these shares describe the mapped part.
18.6% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 2 flood losses here since 2016. 56% of homes were built before 1980, against 50% nationally; the median home dates from 1977.
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 Idaho County
| Expansive clay (limits slab homes) | 8.6% |
| High water table (limits basements) | 12.3% |
| Septic fields very limited | 94.4% |
| Clay swell (LEP, by area) | 3.6% |
| High-swell land (LEP 6%+) | 8.8% |
| Mapped soil | 2,227,977 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Nez Perce | 4% | n/a |
| Bluesprin | 4% | n/a |
| Ferdinand | 3% | n/a |
| Jughandle | 3% | n/a |
| Klickson | 2% | n/a |
| Suttler | 2% | n/a |
How we count · survey areas ID600 (2025-08-27), ID609 (2025-08-27), ID617 (2025-08-27), ID618 (2025-08-27)
What the numbers mean here
Rain over the 12 months to August 2026: 38.49 in, 1.59 in above the 1991-2020 average year of 36.90 in.
USDA rates 94% of the land very limited for septic absorption fields.
With shrink-swell clay on 9% and a shallow water table on 12% of the land, the soil survey points to neither problem across most of Idaho County; conditions still vary lot by lot.
Drought
18.6% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 3 weeks, most recently on the November 4, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 53.7% |
| D1 moderate drought or worse | 18.6% |
| D2 severe or worse | 1.3% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
2 flood losses since 2016, $0 paid. The worst year was 2019, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 36.90 in |
| 12 months to August 2026 | 38.49 in (+1.59) |
| 2025 | 37.49 in (+0.59) |
| Wettest year since 1895 | 1927: 56.73 in |
| Driest year since 1895 | 1935: 22.69 in |
| Days with 1 inch or more, normal at FENN RS (17 mi away) | 5 |
Homes
| Housing units | 8,903 |
| Median year built | 1977 |
| Built before 1980 | 56% |
| Built 2000 or later | 21% |
| Owner-occupied | 81% |
| Median value, owner-occupied | $310,200 |
| 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 |
|---|---|---|---|
| Lewis County, ID | 53 mi | 23% | 33% |
| Clearwater County, ID | 58 mi | 1% | 14% |
| Ravalli County, MT | 67 mi | under 1% | 8% |
| Valley County, ID | 69 mi | 1% | 14% |
| Nez Perce County, ID | 70 mi | 7% | 15% |
| Adams County, ID | 83 mi | 9% | 7% |
| Wallowa County, OR | 85 mi | 31% | 11% |
| Asotin County, WA | 88 mi | 29% | 5% |
Sources: USDA SSURGO (August 27, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status