Clackamas County Area, Oregon
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 Clackamas County Area, Oregon.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Jory silty clay loam, 2 to 8 percent slopes | 30K | Well drained | C | Somewhat limited | Very limited |
| Klickitat stony loam, 30 to 60 percent slopes | 17K | Well drained | B | Very limited | Very limited |
| Bornstedt silt loam, 0 to 8 percent slopes | 16K | Moderately well drained | C | Very limited | Very limited |
| Aloha silt loam, 0 to 3 percent slopes | 16K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Wilhoit-Zygore gravelly loams, 5 to 30 percent slopes | 16K | Well drained | B | Very limited | Very limited |
| Xerochrepts and Haploxerolls, very steep | 14K | Well drained | B | Very limited | Very limited |
| Aschoff cobbly loam, 30 to 60 percent slopes | 14K | Well drained | B | Very limited | Very limited |
| Woodburn silt loam, 3 to 8 percent slopes | 14K | Moderately well drained | C | Very limited | Very limited |
| Klickitat-Kinney complex, 5 to 30 percent slopes | 14K | Well drained | B | Very limited | Very limited |
| Alspaugh clay loam, 2 to 8 percent slopes | 13K | Well drained | C | Somewhat limited | Very limited |
| Alspaugh clay loam, 8 to 15 percent slopes | 13K | Well drained | C | Somewhat limited | Very limited |
| Highcamp very gravelly loam, 30 to 60 percent slopes | 13K | Well drained | A | Very limited | Very limited |
| Aloha silt loam, 3 to 6 percent slopes | 13K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Cazadero silty clay loam, 0 to 7 percent slopes | 13K | Well drained | C | Somewhat limited | Very limited |
| Jory silty clay loam, 8 to 15 percent slopes | 12K | Well drained | C | Somewhat limited | Very limited |
| Zygore-Wilhoit gravelly loams, 30 to 60 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Aschoff-Brightwood complex, 60 to 90 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Kinney cobbly loam, 3 to 20 percent slopes | 12K | Well drained | B | Somewhat limited | Somewhat limited |
| Fernwood-Wilhoit complex, 5 to 30 percent slopes | 10K | Well drained | B | Very limited | Very limited |
| Fernwood-Rock outcrop complex, 50 to 90 percent slopes | 10K | Well drained | B | Very limited | Very limited |
What This Means
Building & Foundations
About 67% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas. A geotechnical assessment is recommended before building.
Septic Systems
About 95% 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.