Carbon County Area, Montana
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 Carbon County Area, Montana.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Rock outcrop-Travessilla complex, steep | 75K | D | Not rated | Not rated | |
| Macar-Cabba clay loams, 8 to 15 percent slopes | 44K | Well drained | B | Somewhat limited | Somewhat limited |
| Limestone outcrop | 44K | D | Not rated | Not rated | |
| Midway-Travessilla association, steep | 42K | Well drained | D | Very limited | Very limited |
| Rentsac-Rock outcrop complex, steep | 34K | Well drained | B | Very limited | Very limited |
| Midway-Travessilla association, hilly | 29K | Well drained | D | Very limited | Very limited |
| Sandstone outcrop | 27K | D | Not rated | Not rated | |
| Charlos loam, 0 to 2 percent slopes | 25K | Well drained | B | Not limited | Very limited |
| Hanson association, very steep | 25K | Well drained | B | Very limited | Very limited |
| Wayden-Castner association, steep | 25K | Well drained | D | Very limited | Very limited |
| Heath clay loam, 8 to 15 percent slopes | 23K | Well drained | C | Very limited | Very limited |
| Heath-Bynum association, steep | 22K | Well drained | C | Very limited | Very limited |
| Shale outcrop | 18K | D | Not rated | Not rated | |
| Absarokee clay loam, 4 to 8 percent slopes | 18K | Well drained | C | Very limited | Very limited |
| Sinnigam channery clay loam, moderately steep | 17K | Well drained | C | Very limited | Very limited |
| Wayden-Cabba association, steep | 16K | Well drained | D | Very limited | Very limited |
| Lismas clay, hilly | 14K | Well drained | D | Very limited | Very limited |
| Heldt silty clay loam, 0 to 2 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Lap-Rock outcrop association, moderately steep | 13K | Well drained | D | Very limited | Very limited |
| Absarokee clay loam, 8 to 15 percent slopes | 12K | Well drained | C | Very limited | Very limited |
What This Means
Building & Foundations
About 56% 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 60% 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.