Clark County, Washington
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). 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 Clark County, Washington.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Hesson clay loam, 0 to 8 percent slopes | 24K | Well drained | C | Somewhat limited | Very limited |
| Cinebar silt loam, 8 to 20 percent slopes | 23K | Well drained | B | Somewhat limited | Somewhat limited |
| Cinebar stony silt loam, 30 to 70 percent slopes | 21K | Well drained | B | Very limited | Very limited |
| Cinebar silt loam, 20 to 30 percent slopes | 20K | Well drained | B | Very limited | Very limited |
| Olympic clay loam, 8 to 20 percent slopes | 18K | Well drained | C | Somewhat limited | Very limited |
| Gee silt loam, 0 to 8 percent slopes | 16K | Moderately well drained | C | Somewhat limited | Very limited |
| Kinney silt loam, 30 to 50 percent slopes | 13K | Well drained | B | Very limited | Very limited |
| Olympic stony clay loam, 3 to 30 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Olympic stony clay loam, 30 to 60 percent slopes | 11K | Well drained | C | Very limited | Very limited |
| Lauren gravelly loam, 0 to 8 percent slopes | 11K | Well drained | B | Not limited | Very limited |
| Cinebar silt loam, 30 to 70 percent slopes | 11K | Well drained | B | Very limited | Very limited |
| Dollar loam, 0 to 5 percent slopes | 11K | Moderately well drained | C | Very limited | Very limited |
| Hesson clay loam, 8 to 20 percent slopes | 11K | Well drained | C | Somewhat limited | Very limited |
| Olympic clay loam, 30 to 60 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Hillsboro loam, 3 to 8 percent slopes | 9K | Well drained | B | Not limited | Very limited |
| Hillsboro silt loam, 0 to 3 percent slopes | 8K | Well drained | B | Not limited | Somewhat limited |
| Hillsboro silt loam, 3 to 8 percent slopes | 8K | Well drained | B | Not limited | Somewhat limited |
| Odne silt loam, 0 to 5 percent slopes | 7K | Poorly drained | D | Very limited | Very limited |
| Hillsboro loam, 0 to 3 percent slopes | 7K | Well drained | B | Not limited | Very limited |
| Cinebar stony silt loam, 3 to 30 percent slopes | 7K | Well drained | B | Very limited | Very limited |
What This Means
Building & Foundations
About 47% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 85% 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.