States / Wisconsin
72 counties · median score 33
Crawl space moisture in Wisconsin
Wisconsin is mixed: 20 of 72 counties score high or elevated, concentrated where drainage is poorest — Taylor County tops the list at 59 — while Vernon County scores just 8. Where you are in the state matters more than the state itself.
- 1Wettest county Taylor County
- 2High or elevated 20 of 72
- 3Median score 33
- 4Driest county Vernon County
Wisconsin's soil, taken as a whole
Across the 35,968,865 acres mapped in these 72 counties, 32% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 51% 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. 71 of the 72 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Excessively drained | 8.4% |
| Somewhat excessively drained | 4.5% |
| Well drained | 38.5% |
| Moderately well drained | 16.5% |
| Somewhat poorly drained | 14.4% |
| Poorly drained | 6.5% |
| Very poorly drained | 11.2% |
Radon. By EPA zone, 28 Wisconsin counties here are zone 1 (highest potential), 44 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 Wisconsin county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Wisconsin numbers
The wettest county, Taylor County, is 40% somewhat poorly drained by dominant condition, with a seasonal water table averaging 0.4 ft below grade across the 93% of acres that report one, and sits in EPA radon zone 2. The driest, Vernon County, is 90% well drained. No Wisconsin 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.