Sierra Valley Area, California, Parts of Sierra, Plumas, and Lassen Counties
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 Sierra Valley Area, California, Parts of Sierra, Plumas, and Lassen Counties.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Ramelli clay | 14K | Poorly drained | C/D | Very limited | Very limited |
| Galeppi loamy coarse sand, 5 to 30 percent slopes | 8K | Well drained | C | Very limited | Very limited |
| Balman-Ramelli complex, 0 to 2 percent slopes | 8K | Somewhat poorly drained | C | Not limited | Very limited |
| Basic rock land | 6K | Excessively drained | Very limited | Very limited | |
| Acidic rock land | 6K | Excessively drained | Very limited | Very limited | |
| Dotta sandy loam, 2 to 9 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Loyalton fine sandy loam | 5K | Moderately well drained | D | Not limited | Very limited |
| Trosi very stony sandy loam, 2 to 15 percent slopes | 5K | Well drained | D | Very limited | Very limited |
| Beckwourth loamy coarse sand | 5K | Somewhat poorly drained | B | Very limited | Very limited |
| Beckwourth-Loyalton complex, saline-alkali, 0 to 2 percent slopes | 5K | Somewhat poorly drained | B | Very limited | Very limited |
| Galeppi sandy loam, 8 to 15 percent slopes | 4K | Well drained | C | Somewhat limited | Very limited |
| Martineck very stony sandy loam, 2 to 30 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Pasquetti mucky silty clay | 4K | Poorly drained | D | Very limited | Very limited |
| James Canyon silt loam, 0 to 2 percent slopes | 4K | Poorly drained | B/D | Very limited | Very limited |
| Ormsby loamy coarse sand, 0 to 2 percent slopes | 4K | Somewhat poorly drained | A | Very limited | Very limited |
| Coolbrith silt loam, 0 to 2 percent slopes | 4K | Somewhat poorly drained | C | Somewhat limited | Very limited |
| Rough broken land | 4K | Excessively drained | D | Very limited | Very limited |
| Calpine-Lovejoy complex, 0 to 5 percent slopes, eroded | 4K | Well drained | A | Not limited | Not limited |
| Portola cobbly coarse sandy loam, 30 to 50 percent slopes | 3K | Well drained | A | Very limited | Very limited |
| Franktown-Aldi-Rock outcrop complex, 30 to 75 percent slopes | 3K | Well drained | D | Very limited | Very limited |
What This Means
Building & Foundations
About 70% 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 96% 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.