Mellette County, South Dakota

Survey Area SD095• South Dakota

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 Mellette 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
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

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.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

Vertisols

High-clay soils that shrink and swell dramatically. Fertile but challenging for foundations and septic systems.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Aridisols

Dry-climate soils with low organic matter. Often have caliche layers that make excavation difficult. Low shrink-swell is good for foundations.

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.