Umatilla County, Oregon
USDA's soil survey flags shrink-swell clay on 7% of Umatilla County's mapped land and a shallow water table under basements on 3%, both below the national shares of 15% and 29%. The soil survey maps 80% of the county's land area; these shares describe the mapped part.
97.7% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 51 flood losses here since 2016, 42% of them in buildings with basements. 52% 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 Umatilla County
| Expansive clay (limits slab homes) | 7.1% |
| High water table (limits basements) | 3.3% |
| Septic fields very limited | 72.2% |
| Clay swell (LEP, by area) | 2.8% |
| High-swell land (LEP 6%+) | 8.5% |
| Mapped soil | 1,653,767 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Walla Walla | 12% | n/a |
| Ritzville | 6% | n/a |
| Gwin | 6% | n/a |
| Athena | 4% | n/a |
| Shano | 4% | n/a |
| Morrow | 4% | n/a |
How we count · survey areas OR667 (2025-09-10)
What the numbers mean here
Rain over the 12 months to August 2026: 17.49 in, 3.24 in below the 1991-2020 average year of 20.73 in.
USDA rates 72% of the land very limited for septic absorption fields.
With shrink-swell clay on 7% and a shallow water table on 3% of the land, the soil survey points to neither problem across most of Umatilla County; conditions still vary lot by lot.
Drought
97.7% 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 47 weeks, most recently on the September 8, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 97.7% |
| D2 severe or worse | 89.1% |
| D3 extreme or worse | 52.3% |
| D4 exceptional | 0% |
Flood losses since 2016
51 flood losses since 2016, $1.5 million paid. The worst year was 2020, with 35. Foundations of the buildings, where recorded: 42% basements, 23% slabs, 23% crawl spaces, 12% elevated. Median water depth outside the building: 16 in.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 1 |
| 2018 | 1 |
| 2019 | 12 |
| 2020 | 35 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 20.73 in |
| 12 months to August 2026 | 17.49 in (-3.24) |
| 2025 | 18.45 in (-2.28) |
| Wettest year since 1895 | 1996: 27.03 in |
| Driest year since 1895 | 1908: 12.86 in |
| Days with 1 inch or more, normal at PENDLETON (9 mi away) | 0.3 |
Homes
| Housing units | 32,199 |
| Median year built | 1979 |
| Built before 1980 | 52% |
| Built 2000 or later | 21% |
| Owner-occupied | 68% |
| Median value, owner-occupied | $282,600 |
| Single-family detached | 62% |
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 |
|---|---|---|---|
| Union County, OR | 41 mi | 26% | 21% |
| Morrow County, OR | 44 mi | 7% | 1% |
| Walla Walla County, WA | 47 mi | 0% | 4% |
| Benton County, WA | 58 mi | 0% | 1% |
| Columbia County, WA | 63 mi | under 1% | 4% |
| Franklin County, WA | 66 mi | 0% | under 1% |
| Wallowa County, OR | 75 mi | 31% | 11% |
| Gilliam County, OR | 76 mi | 3% | under 1% |
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