San Mateo Area, California
The most common soil here is Hugo, on about 11% of the land: a gravelly sandy clay loam, gritty but holds together. Josephine and Lobitos come next.
About 85% of the land drains well; groundwater comes within two feet of the surface under 2% of it.
USDA rates 97% of the land very limited for a standard septic drain field, and 91% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 2% of the land floods occasionally or more, and bedrock lies within 40 inches under 50% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in San Mateo Area, California, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| 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 |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 91% 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 97% 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.