Elmore County Area, Idaho, Parts of Elmore and Owyhee Counties
The most common soil here is Purdam, on about 6% of the land: a silt loam, smooth, like flour. Colthorp and Royal come next.
About 95% of the land drains well.
USDA rates 83% of the land very limited for a standard septic drain field, and 53% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: bedrock lies within 40 inches under 41% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Elmore County Area, Idaho, Parts of Elmore and Owyhee Counties, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Aridisols — dry-climate soils with limited organic matter and often calcium carbonate accumulation. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Elmore County Area, Idaho, Parts of Elmore and Owyhee Counties. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Roanhide-Bauscher-Schoolhouse association, 10 to 60 percent slopes | 110K | Well drained | B | Very limited | Very limited |
| Purdam silt loam, 0 to 4 percent slopes | 102K | Well drained | C | Very limited | Very limited |
| Rainey-Schoolhouse-Oland association, 30 to 70 percent slopes | 87K | Well drained | B | Very limited | Very limited |
| Xeric Torriorthents and Xerollic Camborthids, 8 to 20 percent slopes | 74K | Well drained | B | Very limited | Very limited |
| Colthorp-Kunaton complex, 0 to 8 percent slopes | 62K | Well drained | D | Very limited | Very limited |
| Owsel-Purdam complex, 1 to 12 percent slopes | 57K | Well drained | C | Not limited | Very limited |
| Typic Torriorthents-Badland complex, 20 to 70 percent slopes | 53K | Well drained | B | Very limited | Very limited |
| Badge-Immiant-Rubble land complex, 20 to 70 percent slopes | 47K | Well drained | C | Very limited | Very limited |
| Chilcott-Elijah silt loams, 0 to 12 percent slopes | 44K | Well drained | D | Somewhat limited | Very limited |
| Shano-Truesdale fine sandy loams, 0 to 12 percent slopes | 41K | Well drained | B | Not limited | Not limited |
| Xeric Torriorthents-Xerollic Camborthids complex, 20 to 70 percent slopes | 40K | Well drained | B | Somewhat limited | Somewhat limited |
| Colthorp-Minveno silt loams, 0 to 8 percent slopes, stony | 39K | Well drained | D | Very limited | Very limited |
| Elijah-Purdam silt loams, 0 to 8 percent slopes | 39K | Well drained | C | Somewhat limited | Very limited |
| Typic Torriorthents, 4 to 20 percent slopes | 36K | Well drained | B | Somewhat limited | Very limited |
| Broad Canyon-Grousecreek association, 20 to 70 percent slopes | 35K | Well drained | A | Very limited | Very limited |
| Purdam-Sebree-Owsel complex, 0 to 8 percent slopes | 35K | Well drained | C | Not limited | Very limited |
| Rock outcrop-Rubble land association | 33K | D | Not rated | Not rated | |
| Shano-Owsel complex, 0 to 12 percent slopes | 31K | Well drained | B | Not limited | Not limited |
| Lanktree-Chilcott loams, 0 to 12 percent slopes | 30K | Well drained | C | Somewhat limited | Very limited |
| Royal fine sandy loam, 4 to 12 percent slopes | 29K | Well drained | A | Not limited | Not limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 53% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes. A geotechnical assessment is recommended before building.
Septic Systems
About 83% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.