Oneida County, Idaho
USDA's soil survey flags shrink-swell clay on 5% of Oneida County's mapped land and a shallow water table under basements on 4%, both below the national shares of 15% and 29%. The soil survey maps 53% of the county's land area; these shares describe the mapped part.
100% 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. 59% of homes were built before 1980, against 50% nationally; the median home dates from 1971.
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 Oneida County
| Expansive clay (limits slab homes) | 5.1% |
| High water table (limits basements) | 4.1% |
| Septic fields very limited | 74.8% |
| Clay swell (LEP, by area) | 3.1% |
| High-swell land (LEP 6%+) | 5.1% |
| Mapped soil | 406,854 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Povey | 6% | n/a |
| Bayhook | 5% | n/a |
| Parleys | 4% | n/a |
| Samaria | 4% | n/a |
| Elevator | 3% | n/a |
| Hymas | 3% | n/a |
How we count · survey areas ID713 (2025-08-27), ID715 (2025-08-27)
What the numbers mean here
Rain over the 12 months to August 2026: 15.25 in, 3.11 in below the 1991-2020 average year of 18.36 in.
USDA rates 75% of the land very limited for septic absorption fields.
With shrink-swell clay on 5% and a shallow water table on 4% of the land, the soil survey points to neither problem across most of Oneida County; conditions still vary lot by lot.
Drought
100% 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 38 weeks, most recently on the October 13, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 100% |
| D2 severe or worse | 100% |
| D3 extreme or worse | 91.6% |
| D4 exceptional | 0% |
Flood losses since 2016
1 flood losses since 2016, $0 paid. The worst year was 2018, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 18.36 in |
| 12 months to August 2026 | 15.25 in (-3.11) |
| 2025 | 14.79 in (-3.57) |
| Wettest year since 1895 | 1983: 33.97 in |
| Driest year since 1895 | 1966: 11.20 in |
| Days with 1 inch or more, normal at PLYMOUTH (29 mi away) | 1.6 |
Homes
| Housing units | 2,101 |
| Median year built | 1971 |
| Built before 1980 | 59% |
| Built 2000 or later | 20% |
| Owner-occupied | 88% |
| Median value, owner-occupied | $272,000 |
| Single-family detached | 93% |
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 |
|---|---|---|---|
| Franklin County, ID | 36 mi | 21% | 8% |
| Bannock County, ID | 38 mi | n/a | n/a |
| Power County, ID | 39 mi | 1% | 2% |
| Box Elder County, UT | 48 mi | 2% | 23% |
| Cache County, UT | 51 mi | 22% | 18% |
| Cassia County, ID | 57 mi | 3% | 2% |
| Bear Lake County, ID | 61 mi | 6% | 16% |
| Caribou County, ID | 65 mi | 13% | 4% |
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