Minnesota / Cook County
Score 40 · elevated · #61 of 87 in MN
Crawl space moisture in Cook County, MN
Cook County scores elevated because several moderate signals stack up rather than one dominant one. Where a seasonal water table is reported — 71% of acres — it averages 0.4 ft below grade, shallow enough to reach a typical crawl-space footing.
- 1Water table 0.4 ft
- 2Wet soils 25%
- 3Moisture score 40
- 4EPA radon zone 2
Reading the Cook County soil survey
The score of 40 combines four parts, each from the USDA survey: wet drainage classes contribute 28.4 points of 100 on their own scale, group D soils 46.5, a shallow water table 66, and flooding 5.9; the weights are on the methodology page. The dominant hydrologic group is C (43% of acres): slow infiltration (clay layers).
A water table under two feet is the single most important number here. A crawl-space floor is usually 18 to 36 inches below the joists and often below outside grade, so in a wet season groundwater can stand at or above the crawl-space floor across much of Cook County. Venting cannot fix that; it needs drainage — a perimeter drain to daylight or a sump — before any liner goes down.
Cook County against the rest of Minnesota
Cook County ranks 61 of 87 Minnesota counties, 7 points below the state median of 47. Wetter counties exist in Minnesota, but the soil here still sits well above the national middle. Statewide, 55% of mapped soil is in the wet drainage classes; here it is 25%, below the state figure — the score here comes from a shallow water table rather than drainage class alone. After well drained, the next most common class is very poorly drained at 19%.
Flooding. 5.9% of acres with a flooding class are rated frequent; 0% of acres with a flooding class are rated occasional. Flood-prone soils are a minority here, concentrated along streams; the score mostly reflects what happens between floods.
What it means for a crawl space here
In an elevated county the soil supplies more moisture than average, but a vented crawl space can work if the ground is covered: the code lets vent area drop from 1 sq ft per 150 to 1 per 1500 with a Class I vapor retarder on the ground, which is an admission of how much moisture comes from below. Grading, gutters and a ground cover usually decide whether a crawl space here stays dry before any decision about sealing it.
Radon. EPA radon zone 2. The zone is a county-level prediction; EPA says elevated levels occur in every zone and every home should be tested.
Near Cook County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area MN031; drainage covers 86% of 1,033,100 mapped acres); EPA Map of Radon Zones, county table (June 2024 JSON); IRC R408.3 Unvented crawl space, as adopted in S.C. Code Regs. 8-1221 (LII). Checked 2026-10-23.