Orange County and Part of Riverside County, 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 Orange County and Part of Riverside County, California.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Friant fine sandy loam, 30 to 75 percent slopes | 50K | Well drained | D | Very limited | Very limited |
| Cieneba sandy loam, 30 to 75 percent slopes, eroded | 42K | Somewhat excessively drained | D | Very limited | Very limited |
| Cieneba-Rock outcrop complex, 30 to 75 percent slopes | 37K | Somewhat excessively drained | D | Very limited | Very limited |
| Calleguas clay loam, 50 to 75 percent slopes, eroded | 35K | Well drained | D | Very limited | Very limited |
| Hueneme fine sandy loam, drained | 24K | Poorly drained | A | Not limited | Very limited |
| Myford sandy loam, 2 to 9 percent slopes | 21K | Moderately well drained | C | Somewhat limited | Very limited |
| Metz loamy sand | 21K | Somewhat excessively drained | B | Not limited | Somewhat limited |
| Exchequer-Rock outcrop complex, 30 to 75 percent slopes | 19K | Somewhat excessively drained | D | Very limited | Very limited |
| Rock outcrop-Cieneba complex, 30 to 75 percent slopes | 18K | D | Not rated | Not rated | |
| San Emigdio fine sandy loam, 0 to 2 percent slopes | 16K | Well drained | A | Not limited | Very limited |
| Bolsa silt loam, drained | 14K | Somewhat poorly drained | C | Very limited | Very limited |
| Mocho loam, 0 to 2 percent slopes, warm MAAT, MLRA 19 | 12K | Well drained | B | Not limited | Somewhat limited |
| Alo clay, 15 to 30 percent slopes, dry | 11K | Well drained | D | Very limited | Very limited |
| Alo clay, 30 to 50 percent slopes, warm MAAT, MLRA 20 | 11K | Well drained | D | Very limited | Very limited |
| Chino silty clay loam, drained | 10K | Somewhat poorly drained | C | Very limited | Very limited |
| Metz loamy sand, moderately fine substratum | 9K | Somewhat excessively drained | B | Very limited | Somewhat limited |
| San Emigdio fine sandy loam, moderately fine substratum, 0 to 2 percent slopes | 7K | Well drained | A | Not limited | Very limited |
| Omni clay, drained | 7K | Poorly drained | C | Very limited | Very limited |
| Sorrento clay loam, 0 to 2 percent slopes, warm MAAT, MLRA 19 | 7K | Well drained | C | Somewhat limited | Very limited |
| Sorrento loam, 0 to 2 percent slopes, warm MAAT, MLRA 19 | 6K | Well drained | C | Somewhat limited | Very limited |
What This Means
Building & Foundations
About 64% 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 83% 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.