Adams-Washington Area, Parts of Adams and Washington Counties, Idaho
The most common soil here is Riggins, on about 11% of the land: a very gravelly silt loam, smooth, like flour. Gem and Reywat come next.
About 94% of the land drains well, and 4% stays wet for long stretches.
USDA rates 97% of the land very limited for a standard septic drain field, and 86% 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, and bedrock lies within 40 inches under 73% 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 Adams-Washington Area, Parts of Adams and Washington Counties, Idaho, 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 Adams-Washington Area, Parts of Adams and Washington Counties, Idaho. 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 |
|---|---|---|---|---|---|
| Gem-Reywat complex, stony surface, 2 to 30 percent slopes | 62K | Well drained | D | Very limited | Very limited |
| Meland-Riggins complex, 4 to 30 percent slopes | 60K | Well drained | C | Very limited | Very limited |
| Meland-Riggins complex, stony surface, 30 to 60 percent slopes | 57K | Well drained | C | Very limited | Very limited |
| Gem-Reywat complex, stony surface, 30 to 65 percent slopes | 50K | Well drained | D | Very limited | Very limited |
| Bakeoven-Reywat complex, 2 to 30 percent slopes | 49K | Well drained | D | Very limited | Very limited |
| Riggins extremely stony loam, 30 to 50 percent slopes | 46K | Well drained | D | Very limited | Very limited |
| Bakeoven-Reywat-Rock outcrop complex, stony surface, 30 to 60 percent slopes | 42K | Well drained | D | Very limited | Very limited |
| Riggins extremely stony loam, stony surface, 4 to 30 percent slopes | 35K | Well drained | D | Very limited | Very limited |
| Gem-Bakeoven complex, 2 to 30 percent slopes | 32K | Well drained | D | Very limited | Very limited |
| Demasters loam, 30 to 50 percent slopes | 20K | Well drained | B | Very limited | Very limited |
| Rockly-Riggins complex, stony surface, 4 to 30 percent slopes | 18K | Well drained | D | Very limited | Very limited |
| Bluebell cobbly loam, 35 to 65 percent slopes | 18K | Well drained | C | Very limited | Very limited |
| Gem stony clay loam, 2 to 30 percent slopes | 16K | Well drained | D | Very limited | Very limited |
| Cranecreek-Reywat complex, 2 to 25 percent slopes | 16K | Well drained | D | Somewhat limited | Very limited |
| Water | 15K | Not rated | Not rated | ||
| Gem-Bakeoven complex, stony surface, 30 to 60 percent slopes | 15K | Well drained | D | Very limited | Very limited |
| Deshler-Devnot complex, 2 to 30 percent slopes | 14K | Well drained | D | Very limited | Very limited |
| Klicker stony loam, 30 to 60 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Ticanot very cobbly loam, 4 to 65 percent slopes | 14K | Well drained | D | Very limited | Very limited |
| Oldsferry channery loam, 25 to 65 percent slopes | 13K | Well drained | C | 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 86% 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.