Carter County, Montana
The most common soil here is Gerdrum, on about 6% of the land: a loam, a balanced mix that crumbles in your hand. Neldore and Marvan come next.
About 95% of the land drains well.
USDA rates 65% of the land very limited for a standard septic drain field, and 58% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: bedrock lies within 40 inches under 51% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Carter County, Montana, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Inceptisols — young soils with minimal horizon development but more than Entisols. 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 Carter County, Montana. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Eapa loam, 2 to 8 percent slopes | 92K | Well drained | B | Somewhat limited | Somewhat limited |
| Neldore-Bascovy clays, 4 to 15 percent slopes | 76K | Well drained | D | Very limited | Very limited |
| Gerdrum-Absher complex, 2 to 8 percent slopes | 61K | Well drained | D | Very limited | Not limited |
| Rock outcrop-Moyerson complex, 15 to 50 percent slopes | 50K | D | Not rated | Not rated | |
| Neldore clay, 4 to 15 percent slopes | 46K | Well drained | D | Very limited | Very limited |
| Orinoco-Yawdim silty clay loams, 4 to 15 percent slopes | 46K | Well drained | D | Somewhat limited | Very limited |
| Marvan silty clay, warm, 2 to 8 percent slopes | 46K | Well drained | D | Very limited | Not limited |
| Archin-Absher complex, 2 to 8 percent slopes | 45K | Well drained | D | Somewhat limited | Not limited |
| Marvan silty clay, warm, 0 to 2 percent slopes | 43K | Well drained | D | Very limited | Not limited |
| Archin loam, 2 to 8 percent slopes | 43K | Well drained | C | Not limited | Not limited |
| Gerdrum clay loam, 2 to 8 percent slopes | 42K | Well drained | D | Very limited | Not limited |
| Creed-Gerdrum complex, 2 to 8 percent slopes | 41K | Well drained | C | Very limited | Not limited |
| Moyerson silty clay loam, 4 to 15 percent slopes | 40K | Well drained | D | Very limited | Very limited |
| Moyerson-Orinoco silty clay loams, 4 to 15 percent slopes | 37K | Well drained | D | Very limited | Very limited |
| Absher-Gerdrum complex, 0 to 4 percent slopes | 35K | Moderately well drained | D | Very limited | Somewhat limited |
| Vanda-Marvan complex, 0 to 2 percent slopes | 30K | Well drained | D | Very limited | Very limited |
| Delpoint-Cabbart complex, 8 to 15 percent slopes | 30K | Well drained | C | Somewhat limited | Very limited |
| Havre loam, 0 to 2 percent slopes | 27K | Well drained | B | Very limited | Somewhat limited |
| Yamacall-Cabbart loams, 15 to 35 percent slopes | 26K | Well drained | B | Very limited | Very limited |
| Bickerdyke clay, 0 to 2 percent slopes | 26K | Well drained | C | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 58% 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 65% 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.