San Diego County Area, California
The dominant drainage class is Somewhat excessively 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 San Diego County Area, California.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Acid igneous rock land | 149K | Very limited | Very limited | ||
| Cieneba-Rock outcrop complex, 30 to 75 percent slopes, very stony | 128K | Somewhat excessively drained | D | Very limited | Very limited |
| Cieneba-Fallbrook rocky sandy loams, 30 to 65 percent slopes, eroded | 104K | Somewhat excessively drained | D | Very limited | Very limited |
| Sheephead sandy loam, 30 to 65 percent slopes, eroded, stony | 91K | Well drained | D | Very limited | Very limited |
| Tollhouse coarse sandy loam, 30 to 70 percent slopes, very stony | 86K | Somewhat excessively drained | D | Very limited | Very limited |
| Las Posas loam, 30 to 65 percent slopes, stony | 55K | Well drained | D | Very limited | Very limited |
| San Miguel-Exchequer rocky silt loams, 9 to 70 percent slopes | 45K | Well drained | D | Very limited | Very limited |
| Fallbrook sandy loam, 9 to 15 percent slopes, eroded | 37K | Well drained | C | Somewhat limited | Very limited |
| Tollhouse coarse sandy loam, 5 to 35 percent slopes, eroded, very stony | 36K | Somewhat excessively drained | D | Very limited | Very limited |
| Cieneba rocky coarse sandy loam, 9 to 30 percent slopes, eroded | 32K | Somewhat excessively drained | D | Very limited | Very limited |
| La Posta loamy coarse sand, 5 to 30 percent slopes, eroded | 30K | Somewhat excessively drained | A | Very limited | Very limited |
| La Posta rocky loamy coarse sand, 5 to 30 percent slopes, eroded | 30K | Somewhat excessively drained | A | Very limited | Very limited |
| Mottsville loamy coarse sand, 2 to 9 percent slopes | 30K | Excessively drained | A | Not limited | Very limited |
| Friant rocky fine sandy loam, 30 to 70 percent slopes | 30K | Well drained | D | Very limited | Very limited |
| Carrizo very gravelly sand, 0 to 9 percent slopes | 28K | Excessively drained | A | Very limited | Very limited |
| Redding cobbly loam, dissected, 15 to 50 percent slopes | 28K | Well drained | D | Very limited | Very limited |
| Metamorphic rock land | 26K | Excessively drained | Very limited | Very limited | |
| Fallbrook sandy loam, 15 to 30 percent slopes, eroded | 25K | Well drained | C | Very limited | Very limited |
| Water | 25K | D | Not rated | Not rated | |
| Bancas stony loam, 30 to 65 percent slopes | 24K | Well drained | C | Very limited | Very limited |
What This Means
Building & Foundations
About 91% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas, sandy or gravelly soils with low bearing capacity. A geotechnical assessment is recommended before building.
Septic Systems
About 97% 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.