Targhee National Forest, Idaho and Wyoming

Survey Area ID758• Idaho

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). 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 Targhee National Forest, Idaho and Wyoming. 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
Edgway-Jumpstart-Tophat complex, 15 to 50 percent slopes	118K	Well drained	C	Very limited	Very limited
Juliette-Fritz association, 40 to 70 percent slopes	99K	Well drained	B	Very limited	Very limited
Koffgo-Rhylow-Povey complex, 35 to 60 percent slopes	90K	Well drained	B	Very limited	Very limited
Islandpark-Potrmound-Spliten complex, 0 to 35 percent slopes	79K	Well drained	B	Not limited	Very limited
Gany-Fritz association, 40 to 70 percent slopes	68K	Well drained	B	Very limited	Very limited
Lagall-Povey-Fritz complex, 35 to 70 percent slopes	64K	Well drained	B	Very limited	Very limited
Edgway very gravelly loam, 15 to 40 percent slopes	61K	Well drained	C	Very limited	Very limited
Koffgo-Koffgo, low effective precipitation-Rock outcrop complex, 40 to 70 percent slopes	60K	Well drained	B	Very limited	Very limited
Edgway-Koffgo-Povey association, 15 to 50 percent slopes	51K	Well drained	B	Very limited	Very limited
Flatstone-Koffgo complex, 2 to 15 percent slopes	43K	Well drained	B	Somewhat limited	Very limited
Meegero-Monida complex, 20 to 50 percent slopes	43K	Well drained	B	Very limited	Very limited
Rhylow-Fitzwil association, 4 to 40 percent slopes	42K	Well drained	A	Very limited	Very limited
Huckridge-Koffgo-Povey complex, 4 to 50 percent slopes	39K	Well drained	B	Very limited	Very limited
Koffgo ashy silt loam, 4 to 15 percent slopes	38K	Well drained	B	Somewhat limited	Very limited
Dashiki-Lasac association, 2 to 25 percent slopes	37K	Well drained	A	Not limited	Very limited
Yodal gravelly loam, 35 to 60 percent slopes	36K	Well drained	B	Very limited	Very limited
Lagall very stony ashy loam, 25 to 50 percent slopes	36K	Well drained	B	Very limited	Very limited
Winegar-Bradco complex, 4 to 15 percent slopes	33K	Well drained	B	Somewhat limited	Somewhat limited
Gany-Katpa-Fritz complex, 40 to 70 percent slopes	32K	Well drained	B	Very limited	Very limited
Rubble land-Haplocryepts-Rock outcrop complex, 40 to 70 percent slopes	31K		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.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

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 79% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes. A geotechnical assessment is recommended before building.

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

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.