HomeWashingtonWahkiakum County

Wahkiakum County, Washington

USDA's soil survey flags shrink-swell clay on 4% of Wahkiakum County's mapped land and a shallow water table under basements on 10%, 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 1 flood losses here since 2016. 52% of homes were built before 1980, against 50% nationally; the median home dates from 1978.

Data as of October 13, 2026 · sources

4%

expansive clay: shrink-swell limits slab homes

10%

high water table: limits basements

0%

in drought, October 13, 2026

52%

of homes built before 1980

Soil under Wahkiakum County

Expansive clay (limits slab homes)3.8%
High water table (limits basements)10.1%
Septic fields very limited84.3%
Clay swell (LEP, by area)2.0%
High-swell land (LEP 6%+)3.8%
Mapped soil181,297 acres
Soil seriesShare hereSeries nationally: expansive clay
Lytell24%n/a
Zenker10%n/a
Bunker9%n/a
Germany8%n/a
Elochoman7%n/a
Cathlamet6%n/a
Pacific County: 4%Clatsop County: 1%Columbia County: 7%Cowlitz County: 4%Thurston County: 3%Lewis County: 7%Washington County: 7%Clark County: 3%Wahkiakum County PacificClatsopColumbiaCowlitzThurstonLewisWashingtonClarkWahkiakum
Wahkiakum County (heavy outline) and nearby counties, shaded by expansive clay share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas WA627 (2025-08-28)

What the numbers mean here

Rain over the 12 months to August 2026: 76.26 in, 5.46 in below the 1991-2020 average year of 81.72 in.

USDA rates 84% of the land very limited for septic absorption fields.

With shrink-swell clay on 4% and a shallow water table on 10% of the land, the soil survey points to neither problem across most of Wahkiakum 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.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse7.6%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

1 flood losses since 2016, $9,563 paid. The worst year was 2021, with 1.

YearFlood losses
20160
20170
20180
20190
20200
20211
20220
20230
20240
20250
2026 to date0

Rain

Average year, 1991-202081.72 in
12 months to August 202676.26 in (-5.46)
202570.09 in (-11.63)
Wettest year since 18951950: 115.24 in
Driest year since 18951929: 48.22 in
Days with 1 inch or more, normal at GRAYS RVR HATCHERY (9 mi away)32.8

Homes

Housing units2,250
Median year built1978
Built before 198052%
Built 2000 or later28%
Owner-occupied83%
Median value, owner-occupied$396,800
Single-family detached80%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Foundation repair, US $2,200 to $8,200 Fixr, January 27, 2026
Pier-and-beam repair, US $2,000 to $15,000 Fixr, January 27, 2026
Foundation inspection, US $300 to $600 Fixr, January 31, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Pacific County, WA 25 mi 4% 19%
Clatsop County, OR 25 mi 1% 12%
Columbia County, OR 30 mi 7% 35%
Cowlitz County, WA 36 mi 4% 10%
Thurston County, WA 51 mi 3% 34%
Lewis County, WA 52 mi 7% 20%
Washington County, OR 55 mi 7% 42%
Clark County, WA 58 mi 3% 22%

Sources: USDA SSURGO (August 28, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status