Sierra Valley Area, California, Parts of Sierra, Plumas, and Lassen Counties
The most common soil here is Ramelli, on about 9% of the land: a silty clay, smooth and very sticky when wet. Galeppi and Dotta come next.
About 62% of the land drains well, and 32% stays wet for long stretches; groundwater comes within two feet of the surface under 12% of it.
USDA rates 95% of the land very limited for a standard septic drain field, and 65% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 3% of the land floods occasionally or more, and bedrock lies within 40 inches under 17% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Sierra Valley Area, California, Parts of Sierra, Plumas, and Lassen Counties, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| 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 |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 65% 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 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.