Missouri / Maries County
Score 37 · moderate · #63 of 113 in MO
Crawl space moisture in Maries County, MO
Maries County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 75% of acres — it averages 2.3 ft below grade.
- 1Water table 2.3 ft
- 2Wet soils 9%
- 3Moisture score 37
- 4EPA radon zone 2
Reading the Maries County soil survey
The score of 37 combines four parts, each from the USDA survey: wet drainage classes contribute 27 points of 100 on their own scale, group D soils 51.7, a shallow water table 48.1, and flooding 9.5; the weights are on the methodology page. The dominant hydrologic group is D (40% of acres): very slow infiltration, high runoff (clays, high water table).
At 2.3 ft the seasonal water table is usually below a crawl-space floor, but the 75% of acres that report one are by definition the wettest parts of the county; on those lots, a wet spring can bring water close to the footings.
Maries County against the rest of Missouri
Maries County ranks 63 of 113 Missouri counties, 2 points below the state median of 39. That places it in the middle range, nationally and for the state. Statewide, 32% of mapped soil is in the wet drainage classes; here it is 9%, below the state figure — the score here comes from a shallow water table rather than drainage class alone. After moderately well drained, the next most common class is somewhat excessively drained at 15%.
Flooding. 8.5% of acres with a flooding class are rated frequent; 1% of acres with a flooding class are rated occasional; 2.4% of acres with a flooding class are rated rare. 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 a moderate county the soil record is mixed rather than uniformly wet, so conditions vary from lot to lot. Where the lot drains, the model-code default — a vented crawl space with 1 sq ft of net vent per 150 sq ft of floor, or 1 per 1500 with a Class I vapor retarder on the ground — is a reasonable starting point; where the sections above point to a shallow water table or flood-prone soil on your lot, plan as for an elevated county. Either way, check the site first: grading that falls away from the foundation, gutters and downspouts that discharge well clear of it, and a ground cover over bare earth. A wet crawl space in a moderate county points to one of those first.
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 Maries County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area MO125; drainage covers 100% of 338,910 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.