Nebraska / Lancaster County
Score 36 · moderate · #5 of 93 in NE
Crawl space moisture in Lancaster County, NE
Lancaster County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 58% of acres — it averages 2.1 ft below grade.
- 1Water table 2.1 ft
- 2Wet soils 6%
- 3Moisture score 36
- 4EPA radon zone 1
Reading the Lancaster County soil survey
The score of 36 combines four parts, each from the USDA survey: wet drainage classes contribute 23.7 points of 100 on their own scale, group D soils 61.7, a shallow water table 38.9, and flooding 10.9; the weights are on the methodology page. The dominant hydrologic group is C (48% of acres): slow infiltration (clay layers).
At 2.1 ft the seasonal water table is usually below a crawl-space floor, but the 58% 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.
Lancaster County against the rest of Nebraska
Lancaster County ranks 5 of 93 Nebraska counties, 26 points above the state median of 10. That puts it in the wettest quarter of the state. Statewide, 9% of mapped soil is in the wet drainage classes; here it is 6%, below the state figure — the score here comes from flooding and ponding rather than drainage class alone. After moderately well drained, the next most common class is well drained at 41%.
Flooding. 3.2% of acres with a flooding class are rated frequent; 12.8% of acres with a flooding class are rated occasional. 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. Ponding — water standing at the surface with nowhere to go — affects 18.5% of acres.
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. Lancaster County is in EPA radon zone 1, the highest predicted potential. A sealed crawl space and a radon system share most of their parts — the liner, the sealed seams, a fan — so if you are encapsulating, test for radon first and design both together. EPA itself says the zone map is not a reason to skip testing in zones 2 and 3.
Near Lancaster County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area NE109; drainage covers 95% of 541,715 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.