Douglas County, South Dakota
The most common soil here is Eakin, on about 14% of the land: a silt loam, smooth, like flour. Highmore and Clarno come next.
About 75% of the land drains well, and 10% stays wet for long stretches; groundwater comes within two feet of the surface under 18% of it.
USDA rates 97% of the land very limited for a standard septic drain field, and 14% 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.
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 Douglas 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 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 Douglas 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 |
|---|---|---|---|---|---|
| Eakin-Ethan complex, 2 to 6 percent slopes | 53K | Well drained | C | Not limited | Very limited |
| Clarno-Ethan-Bonilla loams, 1 to 6 percent slopes | 32K | Well drained | B | Not limited | Very limited |
| Highmore-Walke silt loams, 0 to 2 percent slopes | 28K | Well drained | C | Somewhat limited | Very limited |
| Clarno-Bonilla loams, 0 to 2 percent slopes | 17K | Well drained | B | Not limited | Very limited |
| Onita-Tetonka silt loams | 15K | Moderately well drained | C | Somewhat limited | Very limited |
| Highmore silt loam, 0 to 2 percent slopes | 15K | Well drained | C | Somewhat limited | Very limited |
| Tetonka silt loam, 0 to 1 percent slopes | 14K | Poorly drained | C/D | Very limited | Very limited |
| Clarno-Ethan-Prosper loams, 0 to 3 percent slopes | 10K | Well drained | C | Somewhat limited | Very limited |
| Prosper-Tetonka complex | 9K | Moderately well drained | B | Somewhat limited | Very limited |
| Eakin-Ethan complex, 0 to 3 percent slopes | 8K | Well drained | C | Not limited | Very limited |
| DeGrey-Walke silt loams, 0 to 2 percent slopes | 8K | Moderately well drained | D | Somewhat limited | Not limited |
| Eakin-Ethan complex, 6 to 9 percent slopes | 7K | Well drained | C | Not limited | Very limited |
| Houdek-Stickney complex, 0 to 2 percent slopes | 7K | Well drained | C | Somewhat limited | Very limited |
| Highmore silt loam, 2 to 6 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Homme-Onita silty clay loams, 0 to 2 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Clarno-Ethan-Bonilla loams, 2 to 9 percent slopes | 4K | Well drained | B | Not limited | Very limited |
| Bon loam, channeled, 0 to 2 percent slopes, frequently flooded | 4K | Moderately well drained | C | Very limited | Very limited |
| Worthing silty clay loam, 0 to 1 percent slopes | 4K | Very poorly drained | C/D | Very limited | Very limited |
| Delmont-Enet loams, 0 to 2 percent slopes | 3K | Somewhat excessively drained | B | Not limited | Very limited |
| Hoven silt loam, 0 to 1 percent slopes | 3K | Poorly 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
Most soils are generally favorable for residential construction. Standard foundations are usually viable, though site-specific evaluation is always recommended.
Septic Systems
About 97% 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.