Mellette County, South Dakota
The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 Mellette County, South Dakota.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Okaton-Lakoma silty clays, 15 to 40 percent slopes | 124K | Well drained | D | Very limited | Very limited |
| Lakoma-Okaton silty clays, 6 to 15 percent slopes | 55K | Well drained | D | Very limited | Very limited |
| Imlay and Conata soils, 15 to 40 percent slopes | 39K | Well drained | D | Very limited | Very limited |
| Sansarc-Schamber complex, 9 to 35 percent slopes | 27K | Well drained | D | Very limited | Very limited |
| Promise clay, 3 to 6 percent slopes | 25K | Well drained | D | Very limited | Very limited |
| Imlay-Norrest silt loams, 9 to 25 percent slopes | 20K | Well drained | D | Very limited | Very limited |
| Millboro silty clay, 3 to 6 percent slopes | 18K | Well drained | D | Very limited | Very limited |
| Opal-Promise clays, 6 to 9 percent slopes | 17K | Well drained | D | Very limited | Very limited |
| Norrest-Imlay silt loams, 9 to 15 percent slopes | 15K | Well drained | C | Somewhat limited | Very limited |
| Ree and Keya loams, 0 to 2 percent slopes | 15K | Well drained | B | Not limited | Somewhat limited |
| Huggins-Epping silt loams, 5 to 15 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Imlay-Badland association | 14K | Well drained | D | Very limited | Very limited |
| Reliance silty clay loam, 0 to 3 percent slopes | 13K | Well drained | C | Somewhat limited | Very limited |
| Opal clay, mounded, 6 to 9 percent slopes | 13K | Well drained | D | Very limited | Very limited |
| Wendte silty clay loam, channeled | 11K | Moderately well drained | C | Very limited | Very limited |
| Ree and Keya loams, 2 to 5 percent slopes | 11K | Well drained | B | Not limited | Somewhat limited |
| Imlay and Conata soils, 6 to 15 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Schamber-Sansarc complex, 6 to 40 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Promise clay, 0 to 3 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Inavale and Munjor soils | 9K | Well drained | A | Very limited | Very limited |
What This Means
Building & Foundations
About 88% 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 94% 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.