Idaho Soil Surveys
Idaho has 57 USDA soil survey areas covering a wide range of landscapes and soil conditions. The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter, making up roughly 51% of surveyed soils. Aridisols — dry-climate soils with limited organic matter and often calcium carbonate accumulation account for another 14%.
In terms of drainage, 87% of Idaho soils are classified as well drained. Drainage class affects everything from septic system design to basement feasibility to garden planning. Use the survey area pages below to see drainage details for specific counties, or look up any address for an exact soil profile.
Soil Types
Mollisols
51% of surveyed soils
Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.
Aridisols
14% of surveyed soils
Dry-climate soils with low organic matter. Often have caliche layers that make excavation difficult. Low shrink-swell is good for foundations.
Inceptisols
11% of surveyed soils
Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.
Andisols
9% of surveyed soils
Volcanic ash soils — light, porous, and fertile. Excellent drainage, but low density can complicate foundations.
Alfisols
6% of surveyed soils
Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.
Entisols
5% of surveyed soils
Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.
Survey Areas
Ada County, IdahoAdams-Washington Area, Parts of Adams and Washington Counties, IdahoBannock County Area, Idaho, Parts of Bannock and Power CountiesBear Lake County Area, IdahoBenewah County Area, Idaho, Western PartBingham Area, IdahoBlaine County Area, IdahoBoise County Area, Idaho, Western PartBonner County Area, Idaho, Parts of Bonner and Boundary CountiesBonneville County Area, IdahoBoundary County Area, IdahoButte County Area, Idaho, Parts of Butte and Bingham CountiesCamas County Area, IdahoCanyon Area, IdahoCaribou County Area, IdahoCaribou National Forest, Idaho and WyomingCassia County, Idaho, Eastern PartCassia County, Idaho, West PartChallis National Forest, Eastern Part, IdahoChallis National Forest, Western Part, IdahoCity of Rocks National Reserve, IdahoClark County Area, Idaho, Parts of Clark and Butte CountiesClearwater Area, IdahoClearwater National Forest, IdahoCraters of the Moon National Monument and Preserve, IdahoCuster-Lemhi Area, Idaho, Parts of Blaine, Custer, and Lemhi CountiesDuck Valley Indian Reservation, Idaho and NevadaElmore County Area, Idaho, Parts of Elmore and Owyhee CountiesFort Hall Area, Idaho, Parts of Bannock, Bingham, Caribou, and Power CountiesFranklin County Area, IdahoFremont County, Idaho, Western PartGem County Area, IdahoIdaho County Area, Idaho, Western PartIdaho National Engineering Laboratory, IdahoIdaho Panhandle National Forest, Idaho-Washington-MontanaJefferson County, IdahoJerome County and Part of Twin Falls County, IdahoKooskia Area, Idaho County, IdahoKootenai County Area, IdahoLatah County, IdahoLewis and Nez Perce Counties, IdahoMadison County Area, IdahoMiddle Fork Payette River Area, Idaho, Parts of Valley and Boise CountiesMinidoka Area, Idaho, Parts of Minidoka, Blaine, and Lincoln CountiesNez Perce National Forest, IdahoOneida County Area, IdahoOwyhee County Area, IdahoPayette County, IdahoPower County Area, IdahoSalmon National Forest, IdahoSeven Devils Area, IdahoSouth Idaho Forests, IdahoSt. Joe Area, Idaho, Parts of Benewah and Shoshone CountiesTarghee National Forest, Idaho and WyomingTeton Area, Idaho and WyomingValley Area, Idaho, Parts of Adams and Valley CountiesWood River Area, Idaho, Gooding County and Parts of Blaine, Lincoln, and Minidoka Counties