Sully County, South Dakota
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate 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 Sully County, South Dakota.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Agar silt loam, 0 to 2 percent slopes | 92K | Well drained | B | Somewhat limited | Somewhat limited |
| Mobridge silt loam, 0 to 2 percent slopes | 79K | Moderately well drained | C | Somewhat limited | Very limited |
| Highmore silt loam, 0 to 2 percent slopes | 76K | Well drained | C | Somewhat limited | Very limited |
| Water | 45K | Not rated | Not rated | ||
| Eakin-Raber complex, 2 to 6 percent slopes | 33K | Well drained | C | Not limited | Very limited |
| Eakin-Raber complex, 0 to 2 percent slopes | 26K | Well drained | C | Not limited | Very limited |
| Hoven silt loam, 0 to 1 percent slopes | 22K | Poorly drained | D | Very limited | Very limited |
| Agar silt loam, 2 to 6 percent slopes | 22K | Well drained | B | Somewhat limited | Somewhat limited |
| Highmore silt loam, 2 to 6 percent slopes | 20K | Well drained | C | Somewhat limited | Very limited |
| Highmore-Walke silt loams, 0 to 2 percent slopes | 17K | Well drained | C | Somewhat limited | Very limited |
| Onita-Hoven silt loams, 0 to 1 percent slopes | 14K | Moderately well drained | C | Very limited | Very limited |
| Agar-Onita silt loams, 0 to 1 percent slopes | 14K | Well drained | B | Somewhat limited | Somewhat limited |
| Glenham-Ethan-Prosper loams, 1 to 6 percent slopes | 11K | Well drained | C | Not limited | Very limited |
| Sansarc-Opal-Dupree, acid, clays, 6 to 25 percent slopes | 11K | Well drained | D | Very limited | Very limited |
| Raber-Peno loams, 2 to 6 percent slopes | 10K | Well drained | C | Somewhat limited | Very limited |
| Betts loam, 6 to 25 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Raber-Cavo loams, 0 to 2 percent slopes | 9K | Well drained | C | Somewhat limited | Very limited |
| Ethan-Glenham loams, 6 to 9 percent slopes | 9K | Well drained | C | Not limited | Very limited |
| Glenham-Prosper loams, 0 to 2 percent slopes | 9K | Well drained | C | Not limited | Very limited |
| Java-Betts stony loams, 3 to 12 percent slopes | 8K | Well drained | C | Not limited | Very limited |
What This Means
Building & Foundations
Most soils are generally favorable for residential construction. Standard foundations are usually viable, though site-specific evaluation is always recommended.
Septic Systems
About 67% 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
Drainage is generally favorable for gardening. Adding compost and mulch will improve fertility and water retention. Test your soil's pH before planting — most vegetables prefer 6.0-7.0.