Elmore County, Idaho
USDA's soil survey flags shrink-swell clay on 7% of Elmore County's mapped land and a shallow water table under basements on 2%, both below the national shares of 15% and 29%. 85.5% of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 7 flood losses here since 2016. 42% of homes were built before 1980, against 50% nationally; the median home dates from 1988.
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 Elmore County
| Expansive clay (limits slab homes) | 6.8% |
| High water table (limits basements) | 1.6% |
| Septic fields very limited | 65.8% |
| Clay swell (LEP, by area) | 3.3% |
| High-swell land (LEP 6%+) | 9.6% |
| Mapped soil | 1,986,126 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Chilcott | 4% | n/a |
| Roanhide | 3% | n/a |
| Colthorp | 3% | n/a |
| Rainey | 3% | n/a |
| Bauscher | 3% | n/a |
| Kunaton | 3% | n/a |
What the numbers mean here
Rain over the 12 months to August 2026: 17.04 in, 2.25 in below the 1991-2020 average year of 19.29 in.
USDA rates 66% of the land very limited for septic absorption fields.
With shrink-swell clay on 7% and a shallow water table on 2% of the land, the soil survey points to neither problem across most of Elmore County; conditions still vary lot by lot.
Drought
85.5% 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 3 weeks, most recently on the June 30, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 85.5% |
| D2 severe or worse | 48.1% |
| D3 extreme or worse | 33.2% |
| D4 exceptional | 0% |
Flood losses since 2016
7 flood losses since 2016, $45,670 paid. The worst year was 2017, with 7.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 7 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 19.29 in |
| 12 months to August 2026 | 17.04 in (-2.25) |
| 2025 | 20.40 in (+1.11) |
| Wettest year since 1895 | 1970: 32.59 in |
| Driest year since 1895 | 1939: 11.36 in |
| Days with 1 inch or more, normal at HILL CITY 1 W (21 mi away) | 0.7 |
Homes
| Housing units | 12,271 |
| Median year built | 1988 |
| Built before 1980 | 42% |
| Built 2000 or later | 30% |
| Owner-occupied | 66% |
| Median value, owner-occupied | $316,500 |
| Single-family detached | 70% |
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 |
|---|---|---|---|
| Camas County, ID | 36 mi | 19% | 22% |
| Ada County, ID | 39 mi | 20% | 4% |
| Boise County, ID | 43 mi | 3% | 2% |
| Gooding County, ID | 44 mi | 26% | under 1% |
| Canyon County, ID | 64 mi | 1% | 14% |
| Gem County, ID | 65 mi | 19% | 9% |
| Owyhee County, ID | 67 mi | 27% | 2% |
| Lincoln County, ID | 72 mi | 16% | 1% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status