Linn County, Oregon
A shallow water table limits basements on 34% of Linn County's mapped land, a higher share than 53% of US counties and the 5th highest of 35 Oregon counties. Shrink-swell clay limits houses without basements on 25%.
The soil survey maps 66% 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 15 flood losses here since 2016. 53% of homes were built before 1980, against 50% nationally; the median home dates from 1978.
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 Linn County
| Expansive clay (limits slab homes) | 24.9% |
| High water table (limits basements) | 34.3% |
| Septic fields very limited | 95.8% |
| Clay swell (LEP, by area) | 4.4% |
| High-swell land (LEP 6%+) | 24.9% |
| Mapped soil | 964,564 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Dayton | 7% | n/a |
| Honeygrove | 6% | n/a |
| Kinney | 5% | n/a |
| Klickitat | 4% | n/a |
| Harrington | 4% | n/a |
| Nekia | 4% | n/a |
How we count · survey areas OR639 (2025-09-10), OR674 (2025-09-10)
What the numbers mean here
Clay swell averages a linear extensibility of 4.4% by land area here, and 25% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 25% of the mapped land.
Clay shrinks as it dries: 100% of the county is in drought on the latest map, and 25% of Linn County's mapped land has shrink-swell clay.
On 34% of Linn County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 55.90 in, 14.43 in below the 1991-2020 average year of 70.33 in.
USDA rates 96% of the land very limited for septic absorption fields.
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 41 of the last 52 weeks; the most was 100% of its area, in 31 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 | 99.1% |
| D3 extreme or worse | 19.5% |
| D4 exceptional | 0% |
Flood losses since 2016
15 flood losses since 2016, $255,836 paid. The worst year was 2019, with 11.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 11 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 2 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 70.33 in |
| 12 months to August 2026 | 55.90 in (-14.43) |
| 2025 | 61.42 in (-8.91) |
| Wettest year since 1895 | 1996: 112.43 in |
| Driest year since 1895 | 1944: 45.18 in |
| Days with 1 inch or more, normal at FOSTER DAM (8 mi away) | 9 |
Homes
| Housing units | 53,315 |
| Median year built | 1978 |
| Built before 1980 | 53% |
| Built 2000 or later | 23% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $376,400 |
| Single-family detached | 63% |
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 |
|---|---|---|---|
| Marion County, OR | 29 mi | 19% | 40% |
| Lane County, OR | 43 mi | 12% | 14% |
| Benton County, OR | 43 mi | 22% | 24% |
| Clackamas County, OR | 49 mi | 5% | 30% |
| Polk County, OR | 51 mi | 18% | 30% |
| Yamhill County, OR | 65 mi | 31% | 36% |
| Jefferson County, OR | 68 mi | 29% | 1% |
| Lincoln County, OR | 68 mi | 1% | 6% |
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