Custer and Pennington Counties Area, Prairie Parts, South Dakota
The most common soil here is Pierre, on about 10% of the land: a clay, sticky when wet and rock-hard when dry. Samsil and Nunn come next.
About 98% of the land drains well.
USDA rates 84% of the land very limited for a standard septic drain field, and 68% 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 54% 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 Custer and Pennington Counties Area, Prairie Parts, 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 D (very slow infiltration, high 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 Custer and Pennington Counties Area, Prairie Parts, 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 |
|---|---|---|---|---|---|
| Samsil clay, 15 to 40 percent slopes | 122K | Well drained | D | Very limited | Very limited |
| Pierre-Samsil, moderately deep clays, 6 to 25 percent slopes | 83K | Well drained | D | Very limited | Very limited |
| Nunn loam, 2 to 6 percent slopes | 67K | Well drained | C | Somewhat limited | Very limited |
| Pierre clay, 6 to 20 percent slopes | 60K | Well drained | D | Very limited | Very limited |
| Nunn loam, 0 to 2 percent slopes | 55K | Well drained | C | Somewhat limited | Very limited |
| Zigweid-Nihill complex, 6 to 15 percent slopes | 40K | Well drained | B | Somewhat limited | Somewhat limited |
| Satanta loam, 0 to 2 percent slopes | 39K | Well drained | B | Not limited | Somewhat limited |
| Fairburn clay loam, 9 to 40 percent slopes | 37K | Well drained | D | Very limited | Very limited |
| Norrest silty clay loam, 6 to 15 percent slopes | 33K | Well drained | C | Very limited | Very limited |
| Lohmiller silty clay, channeled, 0 to 3 percent slopes, occasionally flooded | 32K | Well drained | C | Very limited | Very limited |
| Midway silty clay loam, 9 to 35 percent slopes | 31K | Well drained | D | Very limited | Very limited |
| Razor-Midway complex, 6 to 15 percent slopes | 31K | Well drained | D | Very limited | Very limited |
| Satanta loam, 2 to 6 percent slopes | 30K | Well drained | B | Not limited | Somewhat limited |
| Fairburn-Orella-Badland complex, 15 to 45 percent slopes | 26K | Well drained | D | Very limited | Very limited |
| Kyle clay, 2 to 6 percent slopes | 25K | Well drained | D | Very limited | Very limited |
| Samsil-Rock outcrop complex, 10 to 50 percent slopes | 23K | Well drained | D | Very limited | Very limited |
| Badland | 22K | Excessively drained | D | Very limited | Very limited |
| Whitewater-Orella clays, 3 to 9 percent slopes | 20K | Well drained | D | Very limited | Very limited |
| Ottumwa clay, 2 to 6 percent slopes | 19K | Well drained | C | Very limited | Very limited |
| Pierre clay, 2 to 6 percent slopes | 19K | Well drained | 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 68% 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 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.