Ada County, Idaho
The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 Ada County, Idaho.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Chilcott-Catchell-Chardoton complex, 0 to 4 percent slopes | 33K | Well drained | D | Somewhat limited | Very limited |
| Purdam silt loam, 0 to 2 percent slopes | 26K | Well drained | C | Somewhat limited | Very limited |
| Tadpole-Corder complex, 0 to 2 percent slopes | 26K | Well drained | B | Not limited | Somewhat limited |
| Catchell-Chilcott-Banbury complex, 1 to 12 percent slopes | 17K | Well drained | D | Very limited | Very limited |
| Elfkin-Dolman-Minveno complex, 1 to 8 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Chilcott-Sebree complex, 2 to 4 percent slopes | 14K | Well drained | D | Somewhat limited | Very limited |
| Chilcott-Sebree complex, 0 to 2 percent slopes | 12K | Well drained | D | Somewhat limited | Very limited |
| Tadpole-Purdam-Trevino complex, 0 to 5 percent slopes | 11K | Well drained | B | Not limited | Somewhat limited |
| Power silt loam, 0 to 2 percent slopes | 10K | Well drained | C | Not limited | Very limited |
| Scism silt loam, bedrock substratum, 2 to 4 percent slopes | 10K | Well drained | C | Somewhat limited | Very limited |
| Chilcott-Sebree complex, bedrock substratum, 2 to 4 percent slopes | 9K | Well drained | D | Very limited | Very limited |
| Colthorp silt loam, 0 to 2 percent slopes | 9K | Well drained | D | Very limited | Very limited |
| Corder-Tadpole complex, 2 to 8 percent slopes | 8K | Well drained | D | Very limited | Very limited |
| Elfkin-Chilcott-Power complex, 0 to 4 percent slopes | 8K | Well drained | C | Very limited | Very limited |
| Paulmyers silt loam, 0 to 3 percent slopes | 8K | Somewhat poorly drained | C | Very limited | Very limited |
| Quailridge-Hullsgulch-Cranegulch complex, 15 to 50 percent slopes | 8K | Well drained | A | Very limited | Very limited |
| Power-McCain silt loams, 2 to 4 percent slopes | 8K | Well drained | C | Not limited | Very limited |
| Truesdale fine sandy loam, 0 to 2 percent slopes | 7K | Well drained | B | Somewhat limited | Very limited |
| Elijah silt loam, 0 to 2 percent slopes | 7K | Well drained | C | Somewhat limited | Very limited |
| Kunaton-Rubble land complex, 2 to 8 percent slopes | 7K | Well drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 35% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 85% 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
Drainage is generally favorable for gardening. Adding compost and mulch will improve fertility and water retention. Test your soil's pH before planting — most vegetables prefer 6.0-7.0.