Fergus 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 Fergus County, Montana.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Thebo clay, 8 to 25 percent slopes | 143K | Well drained | D | Very limited | Very limited |
| Dilts-Julin-Rock outcrop complex, 15 to 50 percent slopes | 103K | Well drained | D | Very limited | Very limited |
| Neldore-Rock outcrop complex, 15 to 60 percent slopes | 87K | Well drained | D | Very limited | Very limited |
| Neldore-Bascovy clays, 25 to 60 percent slopes | 79K | Well drained | D | Very limited | Very limited |
| Winifred-Windham-Eltsac complex, 15 to 45 percent slopes | 54K | Well drained | D | Very limited | Very limited |
| Yawdim-Delpoint-Rock outcrop complex, 25 to 50 percent slopes | 52K | Well drained | D | Very limited | Very limited |
| Dilts-Thebo-Neldore clays, 4 to 60 percent slopes | 50K | Well drained | D | Very limited | Very limited |
| Thebo clay, 2 to 8 percent slopes | 50K | Well drained | D | Very limited | Very limited |
| Thebo-Weingart-Absher clays, 4 to 15 percent slopes | 46K | Well drained | D | Very limited | Very limited |
| Doney-Wayden complex, 15 to 60 percent slopes | 39K | Well drained | D | Very limited | Very limited |
| Yawdim-Abor-Rentsac complex, 8 to 60 percent slopes | 39K | Well drained | D | Very limited | Very limited |
| Neldore-Bascovy clays, 4 to 25 percent slopes | 38K | Well drained | D | Very limited | Very limited |
| Norbert-Eltsac clays, 15 to 60 percent slopes | 38K | Well drained | D | Very limited | Very limited |
| Timberg-Castner complex, 15 to 45 percent slopes | 38K | Well drained | D | Very limited | Very limited |
| Yamac-Delpoint-Yawdim complex, 4 to 25 percent slopes | 36K | Well drained | D | Very limited | Very limited |
| Havre and Harlem soils, occasionally flooded | 33K | Well drained | B | Very limited | Very limited |
| Rock outcrop | 32K | D | Not rated | Not rated | |
| Doney-Windham complex, 15 to 45 percent slopes | 30K | Well drained | C | Very limited | Very limited |
| Eltsac-Norbert clays, 8 to 25 percent slopes | 29K | Well drained | D | Very limited | Very limited |
| Fluvaquentic Haplaquolls, nearly level | 28K | Not rated | Not rated |
What This Means
Building & Foundations
About 94% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 94% 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.