Bennett County, South Dakota
The most common soil here is Valentine, on about 24% of the land: a fine sand, loose sand that holds almost no water. Keith and Canyon come next.
About 89% of the land drains well, and 8% stays wet for long stretches; groundwater comes within two feet of the surface under 4% of it.
USDA rates 76% of the land very limited for a standard septic drain field, and 39% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 4% of the land floods occasionally or more, and bedrock lies within 40 inches under 45% 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 Bennett County, 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 B (moderate infiltration). The most common soil order is Entisols — young soils with little profile development, often on floodplains or steep slopes. 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 Bennett County, 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 |
|---|---|---|---|---|---|
| Valentine fine sand, rolling and hilly, 9 to 60 percent slopes | 110K | Excessively drained | A | Somewhat limited | Very limited |
| Oglala-Canyon loams, 9 to 25 percent slopes | 91K | Well drained | B | Very limited | Very limited |
| Keith-Rosebud silt loams, 2 to 6 percent slopes | 84K | Well drained | B | Somewhat limited | Somewhat limited |
| Canyon-Oglala loams, 18 to 40 percent slopes | 58K | Well drained | D | Very limited | Very limited |
| Canyon-Rock outcrop association, 18 to 40 percent slopes | 36K | Well drained | D | Very limited | Very limited |
| Valentine fine sand, rolling, 9 to 24 percent slopes | 26K | Excessively drained | A | Somewhat limited | Very limited |
| Richfield-Keith silt loams, 0 to 2 percent slopes | 19K | Well drained | B | Somewhat limited | Somewhat limited |
| Richfield-Keith silt loams, 2 to 6 percent slopes | 18K | Well drained | B | Somewhat limited | Very limited |
| Mosher-Minatare complex, 0 to 6 percent slopes | 17K | Somewhat poorly drained | D | Somewhat limited | Very limited |
| Dunday-Anselmo complex, 3 to 9 percent slopes | 17K | Somewhat excessively drained | A | Not limited | Very limited |
| Valentine fine sand, 9 to 25 percent slopes | 16K | Excessively drained | A | Somewhat limited | Very limited |
| Lohmiller silty clay loam, channeled, 0 to 2 percent slopes | 15K | Well drained | C | Very limited | Very limited |
| Tuthill-Anselmo fine sandy loams, 0 to 5 percent slopes | 13K | Well drained | B | Not limited | Very limited |
| Keith silt loam, 3 to 6 percent slopes | 13K | Well drained | B | Not limited | Somewhat limited |
| Mobridge silt loam, 0 to 3 percent slopes | 13K | Well drained | B | Somewhat limited | Somewhat limited |
| Valentine-Tassel complex, hilly | 12K | Excessively drained | A | Very limited | Very limited |
| Keith-Rosebud silt loams, 0 to 2 percent slopes | 12K | Well drained | B | Somewhat limited | Somewhat limited |
| Valentine fine sand, hilly, 24 to 60 percent slopes | 12K | Excessively drained | A | Very limited | Very limited |
| Valentine fine sand, 3 to 9 percent slopes | 11K | Excessively drained | A | Not limited | Very limited |
| Anselmo-Tassel fine sandy loams, 9 to 18 percent slopes | 11K | Well drained | A | 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 39% 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.