Gallatin County Area, Montana
The most common soil here is Brocko, on about 4% of the land: a silt loam, smooth, like flour. Amesha and Amsterdam come next.
About 86% of the land drains well, and 11% stays wet for long stretches; groundwater comes within two feet of the surface under 8% of it.
USDA rates 71% of the land very limited for a standard septic drain field, and 53% 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 33% 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 Gallatin 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 B (moderate infiltration). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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 Gallatin 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 |
|---|---|---|---|---|---|
| Area not surveyed, access denied | 25K | Not rated | Not rated | ||
| Amsterdam-Quagle silt loams, 4 to 8 percent slopes | 17K | Well drained | C | Not limited | Somewhat limited |
| Brocko silt loam, 0 to 4 percent slopes | 15K | Well drained | B | Not limited | Somewhat limited |
| Brocko silt loam, 4 to 8 percent slopes | 15K | Well drained | B | Not limited | Somewhat limited |
| Amesha loam, 0 to 4 percent slopes | 11K | Well drained | B | Not limited | Somewhat limited |
| Crago-Pensore-Rock outcrop complex, 15 to 45 percent slopes | 9K | Well drained | B | Very limited | Very limited |
| Bandy-Riverwash-Bonebasin complex, 0 to 2 percent slopes | 9K | Poorly drained | B/D | Very limited | Very limited |
| Quagle-Brodyk silt loams, 4 to 8 percent slopes | 8K | Well drained | B | Not limited | Somewhat limited |
| Amesha loam, 4 to 8 percent slopes | 8K | Well drained | B | Not limited | Somewhat limited |
| Bacbuster-Wilsall-Castner complex, 15 to 45 percent slopes | 8K | Well drained | D | Very limited | Very limited |
| Hyalite-Beaverton complex, 0 to 4 percent slopes | 8K | Well drained | C | Somewhat limited | Very limited |
| Amsterdam silt loam, 0 to 4 percent slopes | 8K | Well drained | C | Not limited | Somewhat limited |
| Beaverell-Beavwan complex, 0 to 2 percent slopes | 8K | Well drained | B | Somewhat limited | Very limited |
| Brocko silt loam, 8 to 15 percent slopes | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Cabbart-Amesha-Trimad complex, 15 to 45 percent slopes | 8K | Well drained | D | Very limited | Very limited |
| Blackdog silt loam, 0 to 4 percent slopes | 7K | Well drained | C | Not limited | Somewhat limited |
| Bangtail-Copenhaver complex, 8 to 25 percent slopes | 7K | Well drained | C | Very limited | Very limited |
| Amsterdam-Quagle silt loams, 0 to 4 percent slopes | 7K | Well drained | C | Not limited | Somewhat limited |
| Bacbuster-Wilsall-Castner complex, 4 to 15 percent slopes | 7K | Well drained | D | Somewhat limited | Very limited |
| Threeriv-Bonebasin loams, 0 to 2 percent slopes | 7K | Very poorly drained | C/D | 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 53% 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 71% 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.