States / Utah
18 counties · median score 16
Crawl space moisture in Utah
Most of Utah drains well: only 1 of 18 counties score high or elevated, and the median is 16. Tooele County is the exception at 43; crawl-space moisture problems here usually come from grading, gutters and plumbing rather than the soil itself.
- 1Wettest county Tooele County
- 2High or elevated 1 of 18
- 3Median score 16
- 4Driest county Morgan County
Utah's soil, taken as a whole
Across the 28,051,251 acres mapped in these 18 counties, 13% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 14% of acres report a seasonal water table within about two metres. That is a middling figure: wet ground is common in valleys and lowlands but far from universal. 18 of the 18 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Excessively drained | 1.9% |
| Somewhat excessively drained | 7.2% |
| Well drained | 76.5% |
| Moderately well drained | 1.2% |
| Somewhat poorly drained | 1.6% |
| Poorly drained | 1.7% |
| Very poorly drained | 9.9% |
Radon. By EPA zone, 5 Utah counties here are zone 1 (highest potential), 13 zone 2 and 0 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 Utah county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Utah numbers
The wettest county, Tooele County, is 42% well drained by dominant condition, with a seasonal water table averaging 0.1 ft below grade across the 37% of acres that report one, and sits in EPA radon zone 2. The driest, Morgan County, is 92% well drained. No Utah 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.