Alameda County, California, Western Part
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 Alameda County, California, Western Part.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Water | 52K | D | Not rated | Not rated | |
| Novato clay, ponded | 17K | Very poorly drained | D | Very limited | Very limited |
| Danville silty clay loam, 0 to 2 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Urban land | 11K | D | Not rated | Not rated | |
| Clear Lake clay, drained, 0 to 2 percent slopes, MLRA 14 | 9K | Poorly drained | D | Very limited | Very limited |
| Yolo silt loam, 0 to 3 percent slopes, dry, MLRA 14 | 6K | Well drained | B | Not limited | Somewhat limited |
| Botella loam, 0 to 2 percent slopes, MLRA 14 | 5K | Well drained | C | Not limited | Very limited |
| Urban land-Tierra complex, 2 to 5 percent slopes | 5K | Moderately well drained | D | Somewhat limited | Very limited |
| Sycamore silt loam, drained, 0 to 2 percent slopes, MLRA 14 | 5K | Poorly drained | B | Not limited | Somewhat limited |
| Xeropsamments, fill | 5K | A | Somewhat limited | Very limited | |
| Urban land-Clear Lake complex | 4K | D | Not rated | Not rated | |
| Urban land-Baywood complex | 4K | D | Not rated | Not rated | |
| Omni silty clay loam, drained | 4K | Poorly drained | C | Very limited | Very limited |
| Reyes clay, 0 to 2 percent slopes | 4K | Somewhat poorly drained | D | Very limited | Very limited |
| Novato clay, tidally flooded | 4K | Very poorly drained | C/D | Very limited | Very limited |
| Marvin silt loam, saline-alkali | 3K | Somewhat poorly drained | C | Very limited | Very limited |
| Xerorthents-Los Osos complex, 30 to 50 percent slopes | 3K | Not rated | Not rated | ||
| Xerorthents-Millsholm complex, 30 to 50 percent slopes | 3K | B | Very limited | Very limited | |
| Maymen loam, 30 to 75 percent slopes | 3K | Somewhat excessively drained | D | Very limited | Very limited |
| Urban land-Danville complex | 3K | D | Not rated | Not rated |
What This Means
Building & Foundations
About 36% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 45% of soils have significant septic limitations, while others are more suitable. A perc test is essential — conditions vary across the area.
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.