Brule and Buffalo Counties, South Dakota
The most common soil here is Highmore, on about 13% of the land: a silt loam, smooth, like flour. Mobridge and Promise come next.
About 80% of the land drains well, and 6% stays wet for long stretches; groundwater comes within two feet of the surface under 10% of it.
USDA rates 76% of the land very limited for a standard septic drain field, and 37% 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 15% 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 Brule and Buffalo Counties, South Dakota, 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 C (slow infiltration, moderate runoff). 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 Brule and Buffalo Counties, South Dakota. 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 |
|---|---|---|---|---|---|
| Highmore-Mobridge silt loams, 0 to 4 percent slopes | 99K | Well drained | B | Not limited | Somewhat limited |
| Highmore-Java complex, 1 to 5 percent slopes | 97K | Well drained | C | Somewhat limited | Very limited |
| Eakin-DeGrey silt loams, 0 to 2 percent slopes | 76K | Well drained | C | Not limited | Very limited |
| Sansarc-Opal clays, 9 to 25 percent slopes | 52K | Well drained | D | Very limited | Very limited |
| Glenham-Ethan-Prosper loams, 1 to 6 percent slopes | 43K | Well drained | C | Not limited | Very limited |
| Mobridge-Plankinton silt loams | 36K | Moderately well drained | B | Somewhat limited | Somewhat limited |
| Promise clay, 3 to 6 percent slopes | 30K | Well drained | D | Very limited | Very limited |
| Plankinton silt loam | 30K | Poorly drained | D | Very limited | Very limited |
| Water | 26K | Not rated | Not rated | ||
| Promise clay, 0 to 3 percent slopes | 25K | Well drained | D | Very limited | Very limited |
| Highmore-Java complex, 5 to 9 percent slopes | 25K | Well drained | C | Somewhat limited | Very limited |
| Opal-Promise clays, 6 to 9 percent slopes | 24K | Well drained | D | Very limited | Very limited |
| Mobridge silt loam, 0 to 2 percent slopes | 21K | Moderately well drained | C | Somewhat limited | Very limited |
| Chantier-Sansarc clays, 3 to 15 percent slopes | 17K | Well drained | D | Very limited | Very limited |
| Uly silt loam, 2 to 6 percent slopes | 17K | Well drained | B | Not limited | Somewhat limited |
| Java-Betts loams, 9 to 20 percent slopes | 13K | Well drained | B | Very limited | Very limited |
| Opal clay, 3 to 6 percent slopes | 11K | Well drained | D | Very limited | Very limited |
| Beadle-Jerauld complex, 0 to 6 percent slopes | 11K | Well drained | C | Somewhat limited | Very limited |
| Betts-Java loams, 20 to 40 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Glenham-Ethan-Prosper loams, 2 to 9 percent slopes | 9K | Well drained | C | Not 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 37% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 76% 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.