Lewis and Clark County Area, Montana
The most common soil here is Reeder, on about 5% of the land: a loam, a balanced mix that crumbles in your hand. Tolex and Regent come next.
About 90% of the land drains well, and 5% stays wet for long stretches.
USDA rates 84% of the land very limited for a standard septic drain field, and 74% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 2% of the land floods occasionally or more, and bedrock lies within 40 inches under 57% 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 Lewis and Clark County Area, 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 Alfisols — moderately leached forest soils with a clay-enriched subsoil. 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 Lewis and Clark County Area, 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 |
|---|---|---|---|---|---|
| Holter-Castner channery loams, 8 to 45 percent slopes | 50K | Well drained | C | Very limited | Very limited |
| Tolex-Mocmont-Rock outcrop complex, 25 to 60 percent slopes | 39K | Well drained | D | Very limited | Very limited |
| Reeder-Regent-Cabba loams, 2 to 8 percent slopes | 37K | Well drained | D | Very limited | Very limited |
| Reeder-Regent-Cabba loams, 8 to 25 percent slopes | 35K | Well drained | D | Very limited | Very limited |
| Castner-Tolex-Rock outcrop complex, 8 to 60 percent slopes | 32K | Well drained | D | Very limited | Very limited |
| Hauz-Sieben-Tolman channery loams, 8 to 45 percent slopes | 31K | Well drained | C | Very limited | Very limited |
| Reeder-Regent-Castner complex, 8 to 25 percent slopes | 30K | Well drained | D | Very limited | Very limited |
| Fairfield-Beanlake-Winspect stony loams, 2 to 25 percent slopes | 28K | Well drained | C | Somewhat limited | Very limited |
| Castner-Holter-Rock outcrop complex, 15 to 60 percent slopes | 25K | Well drained | D | Very limited | Very limited |
| Beanlake-Winspect stony loams, dry, 2 to 25 percent slopes | 22K | Well drained | B | Somewhat limited | Somewhat limited |
| Mocmont-Tolex complex, 25 to 60 percent slopes | 22K | Well drained | A | Very limited | Very limited |
| Fluvaquents and Fluvaquentic Haplustolls soils, 0 to 4 percent slopes | 22K | Poorly drained | C | Very limited | Very limited |
| Water | 21K | Not rated | Not rated | ||
| Beanlake-Winspect stony loams, 4 to 25 percent slopes | 21K | Well drained | B | Very limited | Very limited |
| Mocmont-Tolex complex, cool, 25 to 60 percent slopes | 21K | Well drained | A | Very limited | Very limited |
| Musselshell-Crago complex, 2 to 8 percent slopes | 20K | Well drained | B | Not limited | Somewhat limited |
| Reeder-Castner-Rock outcrop complex, 8 to 45 percent slopes | 17K | Well drained | C | Very limited | Very limited |
| Sappington-Amesha loams, 1 to 4 percent slopes | 16K | Well drained | B | Not limited | Somewhat limited |
| Regent-Reeder-Work stony loams, 4 to 30 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Marmarth-Delpoint loams, 2 to 8 percent slopes | 14K | Well drained | C | Somewhat 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 74% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 84% 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.