Asotin County Area, Washington (Asotin and Garfield Counties)
The most common soil here is Gwinly, on about 5% of the land: a very cobbly silt loam, smooth, like flour. Laufer and Mallory come next.
About 89% of the land drains well.
USDA rates 97% of the land very limited for a standard septic drain field, and 94% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: bedrock lies within 40 inches under 83% of it.
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 Asotin County Area, Washington (Asotin and Garfield Counties), 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 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 Asotin County Area, Washington (Asotin and Garfield Counties). 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 |
|---|---|---|---|---|---|
| Gwinly-Mallory very stony silt loams, 30 to 70 percent slopes | 20K | Well drained | D | Very limited | Very limited |
| Lickskillet-Schuelke very stony loams, 30 to 70 percent slopes | 20K | Well drained | D | Very limited | Very limited |
| Bolicker-Asotin silt loams, 40 to 90 percent slopes | 18K | Well drained | A | Very limited | Very limited |
| Laufer-Thiessen-Rock outcrop complex, 40 to 90 percent slopes | 17K | Well drained | D | Very limited | Very limited |
| Weissenfels-Nims silt loams, 3 to 8 percent slopes | 17K | Moderately well drained | D | Very limited | Very limited |
| Lickskillet-Schuelke-Rock outcrop complex, 40 to 90 percent slopes | 15K | Well drained | D | Very limited | Very limited |
| Gwinly-Mallory-Rock outcrop complex, 40 to 90 percent slopes | 13K | Well drained | D | Very limited | Very limited |
| Laufer-Thiessen complex, 30 to 70 percent slopes | 11K | Well drained | D | Very limited | Very limited |
| Laufer-Rockly-Rock outcrop complex, 60 to 120 percent slopes | 9K | Well drained | D | Very limited | Very limited |
| Lawyer-Gwinly complex, 40 to 90 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Matheny-Linville-Laufer complex, 40 to 90 percent slopes | 9K | Well drained | B | Very limited | Very limited |
| Neconda silty clay loam, 3 to 6 percent slopes | 7K | Well drained | D | Very limited | Very limited |
| Sweitberg silty clay loam, 3 to 8 percent slopes | 6K | Well drained | D | Very limited | Very limited |
| Nims silt loam, 3 to 8 percent slopes | 6K | Well drained | C | Very limited | Very limited |
| Pataha-Neissenberg silt loams, 3 to 8 percent slopes | 5K | Well drained | C | Very limited | Very limited |
| Harlow-Snell-Harlow variant complex, 3 to 30 percent slopes | 5K | Well drained | D | Very limited | Very limited |
| Cloverland silt loam, very deep, 3 to 8 percent slopes | 5K | Moderately well drained | C | Very limited | Very limited |
| Tolo silt loam, 3 to 30 percent slopes | 5K | Well drained | C | Very limited | Very limited |
| Mallory-Rock outcrop complex, 40 to 90 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Lickskillet-Schuelke very stony loams, 3 to 30 percent slopes | 4K | Well 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
About 94% 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.