Lolo National Forest Area, Montana
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). 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 Lolo National Forest Area, Montana.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| McCay family, broadly convex ridges, weakly weathered metamorphic bedrock | 108K | Well drained | C | Very limited | Very limited |
| Typic Haplocryands-Rock outcrop complex, cirque headwalls | 89K | Well drained | C | Very limited | Very limited |
| Rock outcrop-Specie, extremely stony-Wilde, extremely stony, families, complex, stream breaklands | 86K | D | Not rated | Not rated | |
| McCay family, moderately steep mountain slopes, weakly weathered metasedimentary rock | 79K | Well drained | B | Very limited | Very limited |
| Divers-Oakes families-Rock outcrop complex, glaciated-valley walls | 69K | Well drained | B | Very limited | Very limited |
| Mitten and Tevis families, steep mountain slopes, very stony | 61K | Well drained | B | Very limited | Very limited |
| McCay, cold-McCay families, complex, broadly convex ridges | 60K | Well drained | B | Very limited | Very limited |
| Mitten and Tevis families, moderately steep mountain slopes | 56K | Well drained | B | Very limited | Very limited |
| McCay, Vaywood and Muddycreek families, cirque basins | 47K | Well drained | B | Very limited | Very limited |
| Mitten family, moderately steep mountain slopes, weakly weathered metasedimentary rock | 47K | Well drained | B | Very limited | Very limited |
| Lostbasin family, extremely stony-Rock outcrop complex, stream breaklands | 42K | Well drained | B | Very limited | Very limited |
| Mitten family, extremely stony-Rock outcrop-Tevis family, extremely stony complex, stream breaklands | 42K | Well drained | B | Very limited | Very limited |
| Typic Haplocryands-Constance family-Rock outcrop complex, steep subalpine mountain slopes | 42K | Well drained | D | Very limited | Very limited |
| Beeskove-Bendahl-Foyslake families, complex, moderately steep mountain slopes | 39K | Well drained | B | Very limited | Very limited |
| Vaywood family, glacial-valley floors, extremely bouldery | 37K | Well drained | B | Very limited | Very limited |
| McCay family, steep mountain slopes | 36K | Well drained | B | Very limited | Very limited |
| Lostbasin-Bergquist families, complex, steep mountain slopes, very stony | 35K | Well drained | B | Very limited | Very limited |
| Mitten-Tevis families, complex, moderately steep mountain slopes | 35K | Well drained | B | Very limited | Very limited |
| Broadmoor family, steep mountain slopes, very stony | 33K | Well drained | B | Very limited | Very limited |
| Mitten family, moderately steep mountain slopes | 31K | Well drained | B | Very limited | Very limited |
What This Means
Building & Foundations
About 91% 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 91% 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.