Polk County, Oregon
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). 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 Polk County, Oregon.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Kilchis-Klickitat complex, 60 to 90 percent slopes | 22K | Well drained | D | Very limited | Very limited |
| Woodburn silt loam, 0 to 3 percent slopes | 16K | Moderately well drained | C | Very limited | Very limited |
| Bohannon gravelly loam, 50 to 75 percent slopes | 15K | Well drained | B | Very limited | Very limited |
| Valsetz-Yellowstone complex, 50 to 90 percent slopes | 14K | Well drained | B | Very limited | Very limited |
| Waldo silty clay loam | 14K | Poorly drained | C/D | Very limited | Very limited |
| Dayton silt loam | 13K | Poorly drained | D | Very limited | Very limited |
| Jory silty clay loam, 12 to 20 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Valsetz stony loam, 50 to 75 percent slopes | 11K | Well drained | B | Very limited | Very limited |
| Amity silt loam | 11K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Klickitat gravelly clay loam, 50 to 75 percent slopes | 10K | Well drained | B | Very limited | Very limited |
| Jory silty clay loam, 20 to 30 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Woodburn silt loam, 3 to 12 percent slopes | 9K | Moderately well drained | C | Very limited | Very limited |
| Blachly silty clay loam, 3 to 30 percent slopes | 9K | Well drained | C | Very limited | Very limited |
| Honeygrove silty clay loam, 3 to 25 percent slopes | 8K | Well drained | C | Somewhat limited | Very limited |
| Bellpine silty clay loam, 3 to 12 percent slopes | 7K | Well drained | C | Somewhat limited | Very limited |
| Helmick silt loam, 3 to 12 percent slopes | 7K | Somewhat poorly drained | D | Very limited | Very limited |
| Valsetz stony loam, 3 to 30 percent slopes | 7K | Well drained | B | Very limited | Very limited |
| Astoria silt loam, 5 to 30 percent slopes | 7K | Well drained | B | Very limited | Very limited |
| Astoria silt loam, 30 to 60 percent slopes | 7K | Well drained | B | Very limited | Very limited |
| Jory silty clay loam, 2 to 12 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
What This Means
Building & Foundations
About 89% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 100% 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.