States / Maine
10 counties · median score 46
Crawl space moisture in Maine
Most of Maine sits on soil that holds water: 8 of its 10 counties score high or elevated, led by Piscataquis County at 54. In much of the state a vented crawl space over bare ground is working against the soil it was built on.
- 1Wettest county Piscataquis County
- 2High or elevated 8 of 10
- 3Median score 46
- 4Driest county Oxford County
Maine's soil, taken as a whole
Across the 10,917,972 acres mapped in these 10 counties, 37% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 66% 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. 10 of the 10 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Excessively drained | 3.7% |
| Somewhat excessively drained | 16.3% |
| Well drained | 22.3% |
| Moderately well drained | 21.1% |
| Somewhat poorly drained | 8.3% |
| Poorly drained | 21.8% |
| Very poorly drained | 6.5% |
Radon. By EPA zone, 8 Maine counties here are zone 1 (highest potential), 2 zone 2 and 0 zone 3. With most of the state in zone 1, any crawl-space sealing project here should start with a radon test and be designed to take a radon fan.
Every Maine county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Maine numbers
The wettest county, Piscataquis County, is 25% somewhat poorly drained by dominant condition, with a seasonal water table averaging 0.8 ft below grade across the 77% of acres that report one, and sits in EPA radon zone 1. The driest, Oxford County, is 33% moderately well drained. No Maine 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.