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Whitman County, Washington

A shallow water table limits basements on 15% of Whitman County's mapped land. Shrink-swell clay limits houses without basements on 1%.

100% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 6 flood losses here since 2016. 54% of homes were built before 1980, against 50% nationally; the median home dates from 1977.

Data as of October 13, 2026 · sources

1%

expansive clay: shrink-swell limits slab homes

15%

high water table: limits basements

100%

in drought, October 13, 2026

54%

of homes built before 1980

Soil under Whitman County

Expansive clay (limits slab homes)1.1%
High water table (limits basements)15.2%
Septic fields very limited83.0%
Clay swell (LEP, by area)3.0%
High-swell land (LEP 6%+)2.7%
Mapped soil1,407,507 acres
Soil seriesShare hereSeries nationally: high water table
Palouse25%n/a
Athena14%n/a
Walla Walla14%n/a
Thatuna9%n/a
Kuhl4%n/a
Naff3%n/a
Garfield County: 2%Latah County: 43%Adams County: 2%Columbia County: 4%Benewah County: 40%Spokane County: 16%Asotin County: 5%Nez Perce County: 15%Whitman County GarfieldLatahAdamsColumbiaBenewahSpokaneAsotinNez PerceWhitman
Whitman County (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas WA075 (2025-08-28)

What the numbers mean here

On 15% of Whitman 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: 19.11 in, 1.34 in above the 1991-2020 average year of 17.77 in.

USDA rates 83% 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 52 of the last 52 weeks; the most was 100% of its area, in 20 weeks, most recently on the October 13, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse100%
D1 moderate drought or worse100%
D2 severe or worse83%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

6 flood losses since 2016, $139,260 paid. The worst year was 2025, with 3.

YearFlood losses
20160
20171
20180
20192
20200
20210
20220
20230
20240
20253
2026 to date0

Rain

Average year, 1991-202017.77 in
12 months to August 202619.11 in (+1.34)
202517.28 in (-0.49)
Wettest year since 18951948: 25.57 in
Driest year since 18951929: 10.85 in
Days with 1 inch or more, normal at ST JOHN (13 mi away)0.5

Homes

Housing units22,091
Median year built1977
Built before 198054%
Built 2000 or later23%
Owner-occupied47%
Median value, owner-occupied$359,600
Single-family detached45%

What repairs cost

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

WorkRangeSource
Basement waterproofing, US $3,000 to $10,000 Fixr, February 6, 2026
Sump pump installation, US $800 to $2,000 Fixr, January 31, 2025
Crawl space encapsulation, US $2,000 to $8,000 Fixr, August 29, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Garfield County, WA 33 mi 13% 2%
Latah County, ID 38 mi 5% 43%
Adams County, WA 46 mi under 1% 2%
Columbia County, WA 46 mi under 1% 4%
Benewah County, ID 48 mi 1% 40%
Spokane County, WA 50 mi 3% 16%
Asotin County, WA 52 mi 29% 5%
Nez Perce County, ID 54 mi 7% 15%

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