States / Massachusetts
12 counties · median score 26
Crawl space moisture in Massachusetts
Most of Massachusetts drains well: only 1 of 12 counties score high or elevated, and the median is 26. Bristol County is the exception at 40; crawl-space moisture problems here usually come from grading, gutters and plumbing rather than the soil itself.
- 1Wettest county Bristol County
- 2High or elevated 1 of 12
- 3Median score 26
- 4Driest county Dukes County
Massachusetts's soil, taken as a whole
Across the 4,634,989 acres mapped in these 12 counties, 19% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 44% 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. 11 of the 12 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Excessively drained | 16.9% |
| Somewhat excessively drained | 6.7% |
| Well drained | 41.8% |
| Moderately well drained | 16% |
| Poorly drained | 6.8% |
| Very poorly drained | 11.6% |
| Subaqueous | 0.1% |
Radon. By EPA zone, 3 Massachusetts counties here are zone 1 (highest potential), 9 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 Massachusetts county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Massachusetts numbers
The wettest county, Bristol County, is 27% very poorly drained by dominant condition, with a seasonal water table averaging 1.1 ft below grade across the 57% of acres that report one, and sits in EPA radon zone 2. The driest, Dukes County, is 63% excessively drained. No Massachusetts 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.