Fremont County, Idaho
USDA's soil survey flags shrink-swell clay on 1% of Fremont County's mapped land and a shallow water table under basements on 6%, both below the national shares of 15% and 29%. 58.5% of the county is in drought on the October 13, 2026 Drought Monitor map, down from 98.3% a week earlier.
FEMA's flood data list 6 flood losses here since 2016. 53% of homes were built before 1980, against 50% nationally; the median home dates from 1979.
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 Fremont County
| Expansive clay (limits slab homes) | 0.9% |
| High water table (limits basements) | 5.8% |
| Septic fields very limited | 78.6% |
| Clay swell (LEP, by area) | 2.3% |
| High-swell land (LEP 6%+) | 2.0% |
| Mapped soil | 1,167,098 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Koffgo | 8% | n/a |
| Islandpark | 5% | n/a |
| Lagall | 5% | n/a |
| Vadnais | 4% | n/a |
| Rhylow | 3% | n/a |
| Dashiki | 3% | n/a |
How we count · survey areas ID758 (2025-08-27), ID762 (2025-08-27), WY665 (2025-09-04)
What the numbers mean here
Rain over the 12 months to August 2026: 19.67 in, 2.51 in below the 1991-2020 average year of 22.18 in.
USDA rates 79% of the land very limited for septic absorption fields.
With shrink-swell clay on 1% and a shallow water table on 6% of the land, the soil survey points to neither problem across most of Fremont County; conditions still vary lot by lot.
Drought
58.5% 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 50 weeks, most recently on the September 29, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 58.5% |
| D2 severe or worse | 12.9% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
6 flood losses since 2016, $90,130 paid. The worst year was 2023, with 4.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 4 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 22.18 in |
| 12 months to August 2026 | 19.67 in (-2.51) |
| 2025 | 18.69 in (-3.49) |
| Wettest year since 1895 | 1983: 30.76 in |
| Driest year since 1895 | 1928: 14.71 in |
| Days with 1 inch or more, normal at ASHTON 1N (10 mi away) | 2 |
Homes
| Housing units | 8,810 |
| Median year built | 1979 |
| Built before 1980 | 53% |
| Built 2000 or later | 25% |
| Owner-occupied | 83% |
| Median value, owner-occupied | $314,200 |
| Single-family detached | 83% |
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 |
|---|---|---|---|
| Madison County, ID | 31 mi | under 1% | 14% |
| Teton County, ID | 34 mi | 5% | 12% |
| Clark County, ID | 43 mi | 4% | 4% |
| Jefferson County, ID | 51 mi | 21% | 8% |
| Teton County, WY | 54 mi | 7% | 6% |
| Bonneville County, ID | 57 mi | 11% | 4% |
| Madison County, MT | 80 mi | 3% | 4% |
| Bingham County, ID | 83 mi | under 1% | 2% |
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