Shasta-Trinity National Forest Area, Parts of Humboldt, Siskiyou, Shasta, Tehama, and Trinity Counties, California
The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high 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 Shasta-Trinity National Forest Area, Parts of Humboldt, Siskiyou, Shasta, Tehama, and Trinity Counties, California.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Rock outcrop-Lithic Xerorthents-Lithic Xerochrepts association, moderately steep to steep. | 64K | Somewhat excessively drained | A | Very limited | Very limited |
| Neuns family, 40 to 60 percent slopes. | 61K | Well drained | B | Very limited | Very limited |
| Rock outcrop-Lithic Cryumbrepts-Lithic Xerochrepts association, steep. | 57K | Excessively drained | D | Very limited | Very limited |
| Neuns-Deadwood families complex, 40 to 60 percent slopes. | 56K | Well drained | B | Very limited | Very limited |
| Neuns family, 60 to 80 percent slopes. | 54K | Well drained | B | Very limited | Very limited |
| Rock outcrop, volcanic. | 52K | Excessively drained | D | Very limited | Very limited |
| Water | 48K | D | Not rated | Not rated | |
| Goulding family-Rock outcrop complex, 50 to 80 percent slopes | 42K | Well drained | D | Very limited | Very limited |
| Neuns-Deadwood families complex, 60 to 80 percent slopes. | 38K | Well drained | B | Very limited | Very limited |
| Neuns-Goulding families association, 60 to 80 percent slopes. | 37K | Well drained | B | Very limited | Very limited |
| Marpa-Goulding families association, 40 to 60 percent slopes. | 37K | Well drained | C | Very limited | Very limited |
| Marpa-holland, deep families complex, 40 to 60 percent slopes. | 34K | Well drained | C | Very limited | Very limited |
| Goulding family, 40 to 60 percent slopes. | 33K | Well drained | D | Very limited | Very limited |
| Deadwood-Neuns families complex, 40 to 60 percent slopes. | 30K | Well drained | D | Very limited | Very limited |
| Lava Flow. | 29K | Excessively drained | Very limited | Very limited | |
| Deadwood family, 40 to 60 percent slopes. | 28K | Well drained | D | Very limited | Very limited |
| Rock outcrop-Pachic Xerumbrepts-Dystric Xerochrepts association, steep. | 27K | Well drained | A | Very limited | Very limited |
| Rock outcrop-Lithic Xerumbrepts-Lithic Cryumbrepts association, steep. | 26K | Excessively drained | D | Very limited | Very limited |
| Marpa-Neuns families complex, 40 to 60 percent slopes. | 26K | Well drained | C | Very limited | Very limited |
| Rock outcrop-Lithic Xerumbrepts association, moderately steep to steep. | 25K | Excessively drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 94% 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 94% 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.