Clatsop County, Oregon
USDA's soil survey flags shrink-swell clay on 1% of Clatsop County's mapped land and a shallow water table under basements on 12%, both below the national shares of 15% and 29%. None of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 18 flood losses here since 2016. 58% of homes were built before 1980, against 50% nationally; the median home dates from 1975.
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 Clatsop County
| Expansive clay (limits slab homes) | 0.8% |
| High water table (limits basements) | 12.0% |
| Septic fields very limited | 88.6% |
| Clay swell (LEP, by area) | 2.8% |
| High-swell land (LEP 6%+) | 1.0% |
| Mapped soil | 558,897 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Rinearson | 12% | n/a |
| Skipanon | 10% | n/a |
| Templeton | 8% | n/a |
| Klootchie | 8% | n/a |
| Necanicum | 4% | n/a |
| Caterl | 3% | n/a |
How we count · survey areas OR007 (2025-09-09)
What the numbers mean here
Rain over the 12 months to August 2026: 83.29 in, 5.55 in below the 1991-2020 average year of 88.84 in.
USDA rates 89% of the land very limited for septic absorption fields.
With shrink-swell clay on 1% and a shallow water table on 12% of the land, the soil survey points to neither problem across most of Clatsop County; conditions still vary lot by lot.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 8 of the last 52 weeks; the most was 100% of its area, on the October 21, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 8.3% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
18 flood losses since 2016, $175,152 paid. The worst year was 2021, with 5.
| Year | Flood losses |
|---|---|
| 2016 | 3 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 1 |
| 2021 | 5 |
| 2022 | 2 |
| 2023 | 3 |
| 2024 | 1 |
| 2025 | 2 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 88.84 in |
| 12 months to August 2026 | 83.29 in (-5.55) |
| 2025 | 80.20 in (-8.64) |
| Wettest year since 1895 | 1950: 124.74 in |
| Driest year since 1895 | 1929: 51.77 in |
| Days with 1 inch or more, normal at SEASIDE (11 mi away) | 20 |
Homes
| Housing units | 23,395 |
| Median year built | 1975 |
| Built before 1980 | 58% |
| Built 2000 or later | 19% |
| Owner-occupied | 63% |
| Median value, owner-occupied | $468,300 |
| 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 |
|---|---|---|---|
| Wahkiakum County, WA | 25 mi | 4% | 10% |
| Columbia County, OR | 31 mi | 7% | 35% |
| Pacific County, WA | 37 mi | 4% | 19% |
| Tillamook County, OR | 39 mi | 1% | 5% |
| Washington County, OR | 44 mi | 7% | 42% |
| Cowlitz County, WA | 51 mi | 4% | 10% |
| Yamhill County, OR | 57 mi | 31% | 36% |
| Clark County, WA | 61 mi | 3% | 22% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status