States / Alaska
2 counties · median score 36
Crawl space moisture in Alaska
Most of Alaska drains well: only 0 of 2 counties score high or elevated, and the median is 36. Yakutat City and Borough is the exception at 36; crawl-space moisture problems here usually come from grading, gutters and plumbing rather than the soil itself.
- 1Wettest county Yakutat City and Borough
- 2High or elevated 0 of 2
- 3Median score 36
- 4Driest county Haines Borough
Alaska's soil, taken as a whole
Across the 1,709,101 acres mapped in these 2 counties, 44% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 29% of acres report a seasonal water table within about two metres. That is a wet state by any measure; a third or more of its land holds water near the surface for part of the year. 2 of the 2 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Somewhat excessively drained | 1.4% |
| Well drained | 50.7% |
| Moderately well drained | 3.7% |
| Somewhat poorly drained | 13.3% |
| Poorly drained | 7.8% |
| Very poorly drained | 23% |
Radon. By EPA zone, 0 Alaska counties here are zone 1 (highest potential), 0 zone 2 and 2 zone 3. EPA says to test regardless of zone; a sealed crawl space is the cheapest moment to add radon venting if a test calls for it.
Every Alaska county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Alaska numbers
The wettest county, Yakutat City and Borough, is 39% well drained by dominant condition, with a seasonal water table averaging 0.8 ft below grade across the 34% of acres that report one, and sits in EPA radon zone 3. The driest, Haines Borough, is 78% well drained. No Alaska county reaches the high tier.
The score is a guide to the soil, not to a house: a well-graded lot with working gutters in a high county can have a dry crawl space, and a bad downspout can flood one in a low county. The R408 calculator sizes venting or encapsulation for any footprint.
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted; EPA Map of Radon Zones, county table (June 2024 JSON). Checked 2026-10-23.