Crawl space moisture in Utah County, UT

55% of Utah County's soil falls in hydrologic group D or a dual D group: clays and high water tables that shed water slowly. Where a seasonal water table is reported — 27% of acres — it averages 2.8 ft below grade.

Size venting or encapsulation

1Water table 2.8 ft
2Wet soils 33%
3Moisture score 33
4EPA radon zone 2

Share of mapped soil acres in Utah County, UT by NRCS drainage class (dominant condition), bars to scale; wetter classes highlighted. Covers 64% of mapped acres.

Dominant drainage

Well drained

56% of acres

Group D soils

55%

slow infiltration

Flood-prone acres

32%

any flooding frequency

Ponding

acres where water ponds

Reading the Utah County soil survey

The score of 33 combines four parts, each from the USDA survey: wet drainage classes contribute 30.4 points of 100 on their own scale, group D soils 59.9, a shallow water table 15.5, and flooding 15.4; the weights are on the methodology page. The dominant hydrologic group is D (50% of acres): very slow infiltration, high runoff (clays, high water table).

Hydrologic soil groups in Utah County by share of acres, columns to scale. Group D and dual groups (x/D) shed water slowly and hold it near the surface.

At 2.8 ft the seasonal water table is usually below a crawl-space floor, but the 27% 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.

Utah County against the rest of Utah

Utah County ranks 3 of 18 Utah counties, 17 points above the state median of 16. Only 2 other counties in the state score higher. Statewide, 13% of mapped soil is in the wet drainage classes; here it is 33%, half again the state figure or more. After well drained, the next most common class is poorly drained at 18%.

Flooding. 6.5% of acres with a flooding class are rated frequent; 9.2% of acres with a flooding class are rated occasional; 16.6% of acres with a flooding class are rated rare. That is a large flood-prone share; a crawl space in the floodplain needs flood vents under most local floodplain ordinances, which is a separate rule from R408 and can rule out a fully sealed design.

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 Utah County by score

Box Elder County 33 Salt Lake County 29 Tooele County 43Washington County 19

All 18 Utah counties

Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area UT621; drainage covers 64% of 301,088 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.