Gilliam County, Oregon
The most common soil here is Lickskillet, on about 13% of the land: a gravelly loam, a balanced mix that crumbles in your hand. Ritzville and Morrow come next.
About 98% of the land drains well.
USDA rates 80% of the land very limited for a standard septic drain field, and 76% 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 65% 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 Gilliam County, Oregon, 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 Gilliam County, Oregon. 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 |
|---|---|---|---|---|---|
| Lickskillet-Rock outcrop complex, 40 to 70 percent slopes | 92K | Well drained | D | Very limited | Very limited |
| Ritzville silt loam, 2 to 7 percent slopes | 59K | Well drained | B | Not limited | Somewhat limited |
| Wrentham-Rock outcrop complex, 35 to 70 percent slopes | 58K | Well drained | C | Very limited | Very limited |
| Lickskillet very stony loam, 7 to 40 percent slopes | 46K | Well drained | D | Very limited | Very limited |
| Condon and Valby silt loams, 1 to 7 percent slopes | 44K | Well drained | C | Very limited | Very limited |
| Morrow silt loam, 1 to 7 percent slopes | 36K | Well drained | C | Very limited | Very limited |
| Bakeoven-Condon complex, 2 to 20 percent slopes | 35K | Well drained | D | Very limited | Very limited |
| Condon and Valby silt loams, 7 to 12 percent slopes | 27K | Well drained | C | Very limited | Very limited |
| Ritzville silt loam, 7 to 12 percent slopes | 25K | Well drained | B | Somewhat limited | Somewhat limited |
| Mikkalo silt loam, 7 to 12 percent slopes | 21K | Well drained | C | Very limited | Very limited |
| Bakeoven-Morrow complex, 2 to 20 percent slopes | 19K | Well drained | D | Very limited | Very limited |
| Waha-Rockly complex, 2 to 20 percent slopes | 16K | Well drained | D | Very limited | Very limited |
| Mikkalo silt loam, 2 to 7 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Olex silt loam, 0 to 5 percent slopes | 13K | Well drained | B | Not limited | Somewhat limited |
| Willis silt loam, 2 to 5 percent slopes | 12K | Well drained | C | Somewhat limited | Very limited |
| Ritzville silt loam, 12 to 20 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Roloff-Rock outcrop complex, 1 to 20 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Water | 12K | Not rated | Not rated | ||
| Ritzville silt loam, 20 to 40 percent north slopes | 10K | Well drained | B | Very limited | Very limited |
| Morrow silt loam, 7 to 12 percent slopes | 9K | 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 76% 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 80% 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.