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Whatcom County, Washington
A shallow water table limits basements on 25% of Whatcom County's mapped land. Shrink-swell clay limits houses without basements on 1%.
The soil survey maps 79% of the county's land area; these shares describe the mapped part. 99.4% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 697 flood losses here since 2016, 6% of them in buildings with basements. 40% of homes were built before 1980, against 50% nationally; the median home dates from 1989.
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 Whatcom County
| Expansive clay (limits slab homes) | 0.5% |
| High water table (limits basements) | 25.1% |
| Septic fields very limited | 88.6% |
| Clay swell (LEP, by area) | 1.3% |
| High-swell land (LEP 6%+) | 0.5% |
| Mapped soil | 1,063,060 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Doubtful | 4% | n/a |
| Whatcom | 3% | n/a |
| Stetattle | 2% | n/a |
| Perfect | 2% | n/a |
| Spickard | 2% | n/a |
| Treen | 2% | n/a |
How we count · survey areas WA673 (2025-08-28), WA749 (2025-08-28), WA774 (2025-08-28)
What the numbers mean here
On 25% of Whatcom 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: 78.89 in, 6.71 in above the 1991-2020 average year of 72.18 in.
USDA rates 89% of the land very limited for septic absorption fields.
Drought
99.4% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 23 of the last 52 weeks; the most was 100% of its area, in 7 weeks, most recently on the December 2, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 99.4% |
| D2 severe or worse | 61.9% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
697 flood losses since 2016, $46.1 million paid. The worst year was 2021, with 329. Foundations of the buildings, where recorded: 6% basements, 24% slabs, 63% crawl spaces, 7% elevated. Median water depth outside the building: 22 in.
| Year | Flood losses |
|---|---|
| 2016 | 6 |
| 2017 | 1 |
| 2018 | 2 |
| 2019 | 0 |
| 2020 | 26 |
| 2021 | 329 |
| 2022 | 28 |
| 2023 | 1 |
| 2024 | 4 |
| 2025 | 297 |
| 2026 to date | 3 |
Rain
| Average year, 1991-2020 | 72.18 in |
| 12 months to August 2026 | 78.89 in (+6.71) |
| 2025 | 73.80 in (+1.62) |
| Wettest year since 1895 | 1990: 91.65 in |
| Driest year since 1895 | 1929: 42.28 in |
| Days with 1 inch or more, normal at UPPER BAKER DAM (15 mi away) | 30.7 |
Homes
| Housing units | 103,520 |
| Median year built | 1989 |
| Built before 1980 | 40% |
| Built 2000 or later | 32% |
| Owner-occupied | 64% |
| Median value, owner-occupied | $585,800 |
| 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 |
|---|---|---|---|
| Skagit County, WA | 26 mi | under 1% | 46% |
| Snohomish County, WA | 55 mi | 1% | 72% |
| Island County, WA | 61 mi | 0% | 65% |
| San Juan County, WA | 62 mi | 0% | 47% |
| Chelan County, WA | 88 mi | under 1% | 2% |
| Kitsap County, WA | 91 mi | under 1% | 65% |
| King County, WA | 95 mi | under 1% | 38% |
| Okanogan County, WA | 98 mi | 0% | 3% |
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