Idaho / Camas County
Score 21 · moderate · #3 of 33 in ID
Crawl space moisture in Camas County, ID
Camas County scores moderate: no single wet-soil signal dominates its mapped acres. Where a seasonal water table is reported — 21% of acres — it averages 3 ft below grade.
- 1Water table 3 ft
- 2Wet soils 13%
- 3Moisture score 21
- 4EPA radon zone 1
Reading the Camas County soil survey
The score of 21 combines four parts, each from the USDA survey: wet drainage classes contribute 13.3 points of 100 on their own scale, group D soils 44.9, a shallow water table 11.4, and flooding 13.2; the weights are on the methodology page. The dominant hydrologic group is C (44% of acres): slow infiltration (clay layers).
At 3 ft the seasonal water table is usually below a crawl-space floor, but the 21% 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.
Camas County against the rest of Idaho
Camas County ranks 3 of 33 Idaho counties, 9 points above the state median of 12. Only 2 other counties in the state score higher. Statewide, 5% of mapped soil is in the wet drainage classes; here it is 13%, half again the state figure or more. After well drained, the next most common class is somewhat poorly drained at 8%.
Flooding. 13.2% of acres with a flooding class are rated frequent. 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. Camas 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 Camas County by score
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted (survey area ID673; drainage covers 99% of 347,602 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.