Yellowstone County, 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 Yellowstone County, Montana.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Lismas clay, 15 to 35 percent slopes | 111K | Well drained | D | Very limited | Very limited |
| Blacksheep, dry-Cabbart, dry-Rock outcrop, complex, 8 to 60 percent slopes | 88K | Well drained | D | Very limited | Very limited |
| McRae-Bainville loams, 7 to 15 percent slopes | 70K | Well drained | B | Somewhat limited | Very limited |
| Hilly, gravelly land | 68K | Well drained | D | Very limited | Very limited |
| Delpoint-Cabbart loams, 2 to 8 percent slopes | 61K | Well drained | C | Somewhat limited | Very limited |
| Cabbart-Delpoint loams, 4 to 15 percent slopes | 57K | Well drained | D | Very limited | Very limited |
| Midway-Shale outcrop complex, 4 to 35 percent slopes | 55K | Well drained | D | Very limited | Very limited |
| Bainville clay loam, 7 to 15 percent slopes, shallow | 37K | Well drained | D | Very limited | Very limited |
| McRae loam, 4 to 7 percent slopes | 32K | Well drained | B | Not limited | Somewhat limited |
| Maginnis channery clay loam, 15 to 35 percent slopes | 31K | Well drained | D | Very limited | Very limited |
| Bainville-Lohmiller complex, 15 to 35 percent slopes | 30K | Well drained | D | Very limited | Very limited |
| Cabbart-Bonfri loams, 2 to 8 percent slopes | 29K | Well drained | D | Very limited | Very limited |
| Bainville-Shale outcrop complex, 7 to 25 percent slopes | 28K | Well drained | D | Very limited | Very limited |
| Lohmiller-Bainville complex, 4 to 15 percent slopes | 28K | Well drained | D | Very limited | Very limited |
| Bonfri-Cabbart loams, 0 to 4 percent slopes | 28K | Well drained | C | Somewhat limited | Very limited |
| Blacksheep-Twilight complex, 4 to 25 percent slopes | 27K | Well drained | D | Very limited | Very limited |
| Pierre-Lismas clays, 7 to 15 percent slopes | 25K | Well drained | D | Very limited | Very limited |
| Danvers silty clay loam, 2 to 4 percent slopes | 25K | Well drained | C | Very limited | Very limited |
| McRae loam, 1 to 4 percent slopes | 24K | Well drained | B | Not limited | Somewhat limited |
| Vananda silty clay, 0 to 1 percent slopes | 23K | Well drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 75% 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 93% 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.