San Bernardino County Southwestern Part, California
The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is A (high infiltration, low 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 San Bernardino County Southwestern Part, California.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Tujunga loamy sand, 0 to 5 percent slopes | 43K | Somewhat excessively drained | A | Very limited | Very limited |
| Tujunga gravelly loamy sand, 0 to 9 percent slopes | 37K | Somewhat excessively drained | A | Very limited | Very limited |
| Hanford coarse sandy loam, 2 to 9 percent slopes | 27K | Well drained | A | Very limited | Very limited |
| Soboba stony loamy sand, 2 to 9 percent slopes | 23K | Excessively drained | A | Very limited | Very limited |
| Delhi fine sand | 20K | Somewhat excessively drained | A | Not limited | Very limited |
| Cieneba-Rock outcrop complex, 30 to 50 percent slopes, MLRA 20 | 15K | Somewhat excessively drained | D | Very limited | Very limited |
| Soboba gravelly loamy sand, 0 to 9 percent slopes | 12K | Excessively drained | A | Very limited | Very limited |
| Saugus sandy loam, 30 to 50 percent slopes | 9K | Well drained | B | Very limited | Very limited |
| Psamments, Fluvents and Frequently flooded soils | 9K | Somewhat excessively drained | A | Very limited | Very limited |
| Ramona sandy loam, 2 to 9 percent slopes, MLRA 19 | 8K | Well drained | C | Not limited | Very limited |
| Greenfield sandy loam, 2 to 9 percent slopes | 8K | Well drained | A | Not limited | Very limited |
| Grangeville fine sandy loam, warm MAAT, MLRA 19 | 8K | Somewhat poorly drained | A | Very limited | Very limited |
| Hanford sandy loam, 0 to 2 percent slopes | 7K | Well drained | A | Very limited | Very limited |
| Fontana clay loam, 30 to 50 percent slopes | 7K | Well drained | C | Very limited | Very limited |
| Chino silt loam | 7K | Somewhat poorly drained | C | Very limited | Very limited |
| Gaviota-Rock outcrop complex | 5K | Somewhat excessively drained | D | Very limited | Very limited |
| Tollhouse sandy loam, 30 to 50 percent slopes | 4K | Excessively drained | D | Very limited | Very limited |
| Hilmar loamy fine sand | 4K | Somewhat poorly drained | B | Very limited | Somewhat limited |
| Ramona sandy loam, 9 to 15 percent slopes | 3K | Well drained | C | Somewhat limited | Very limited |
| Ramona sandy loam, 15 to 30 percent slopes, eroded | 3K | Well drained | C | Very limited | Very limited |
What This Means
Building & Foundations
About 84% 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, sandy or gravelly soils with low bearing capacity. A geotechnical assessment is recommended before building.
Septic Systems
About 98% of soils are rated "very limited" for septic absorption fields. The well-drained soils may actually drain too fast for standard leach fields, allowing effluent to reach groundwater. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Soils tend to drain very quickly, meaning nutrients and water don't stick around long. Raised beds with amended soil, drip irrigation, and heavy mulching will give the best results. Compost is your best friend here — it improves water retention dramatically.