San Mateo Area, California
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate 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 Mateo Area, California.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Hugo and Josephine sandy loams, very steep | 15K | Well drained | A | Very limited | Very limited |
| Hugo and Josephine loams, very steep | 12K | Well drained | B | Very limited | Very limited |
| Butano loam, very steep | 11K | Well drained | C | Very limited | Very limited |
| Rough broken land | 9K | Excessively drained | Very limited | Very limited | |
| Hugo and Josephine sandy loams, very steep, eroded | 6K | Well drained | A | Very limited | Very limited |
| Miramar coarse sandy loam, very steep, eroded | 6K | Well drained | C | Very limited | Very limited |
| Lobitos loam, steep, eroded | 5K | Well drained | C | Very limited | Very limited |
| Gazos loam, very steep, eroded | 5K | Well drained | C | Very limited | Very limited |
| Santa Lucia loam, very steep, eroded | 5K | Well drained | C | Very limited | Very limited |
| Lobitos loam, very steep, eroded | 4K | Well drained | C | Very limited | Very limited |
| Lobitos loam, moderately steep, eroded | 3K | Well drained | C | Very limited | Very limited |
| Santa Lucia loam, steep, eroded | 3K | Well drained | C | Very limited | Very limited |
| Mindego clay loam, very steep | 3K | Well drained | C | Very limited | Very limited |
| Santa Lucia stony loam, very steep, eroded | 2K | Well drained | C | Very limited | Very limited |
| Tierra loam, steep, eroded | 2K | Moderately well drained | D | Very limited | Very limited |
| Santa Lucia loam, moderately steep, eroded | 2K | Well drained | C | Very limited | Very limited |
| Pomponio loam, moderately steep, eroded | 2K | Moderately well drained | C | Very limited | Very limited |
| Hugo and Josephine sandy loams, steep, eroded | 2K | Well drained | A | Very limited | Very limited |
| Tierra loam, moderately steep, eroded | 2K | Moderately well drained | D | Very limited | Very limited |
| Miramar coarse sandy loam, steep, eroded | 2K | Well drained | C | Very limited | Very limited |
What This Means
Building & Foundations
About 100% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes. A geotechnical assessment is recommended before building.
Septic Systems
About 100% 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.