El Dorado Area, California
The most common soil here is Auburn, on about 16% of the land: a silt loam, smooth, like flour. Mariposa and Josephine come next.
About 88% of the land drains well.
USDA rates 97% of the land very limited for a standard septic drain field, and 88% 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 60% 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 El Dorado 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 D (very slow infiltration, high runoff). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. 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 El Dorado 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 |
|---|---|---|---|---|---|
| Auburn very rocky silt loam, 2 to 30 percent slopes | 63K | Well drained | D | Very limited | Very limited |
| Mariposa very rocky silt loam, 3 to 50 percent slopes | 33K | Well drained | C | Very limited | Very limited |
| Auburn very rocky silt loam, 30 to 50 percent slopes | 29K | Well drained | D | Very limited | Very limited |
| Mariposa very rocky silt loam, 50 to 70 percent slopes | 25K | Well drained | C | Very limited | Very limited |
| Mariposa-Josephine very rocky loams, 15 to 50 percent slopes | 21K | Well drained | C | Very limited | Very limited |
| Serpentine rock land | 18K | Very limited | Very limited | ||
| Auburn silt loam, 2 to 30 percent slopes | 16K | Well drained | D | Very limited | Very limited |
| Josephine silt loam, 15 to 30 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Metamorphic rock land | 12K | Very limited | Very limited | ||
| Josephine very rocky silt loam, 9 to 50 percent slopes | 11K | Well drained | B | Very limited | Very limited |
| Josephine very rocky loam, 15 to 50 percent slopes | 11K | Well drained | B | Very limited | Very limited |
| Water | 10K | D | Not rated | Not rated | |
| Boomer very rocky loam, 30 to 50 percent slopes | 10K | Well drained | C | Very limited | Very limited |
| Rescue extremely stony sandy loam, 3 to 50 percent slopes, eroded | 10K | Well drained | C | Very limited | Very limited |
| McCarthy cobbly loam, 9 to 50 percent slopes | 9K | Well drained | B | Very limited | Very limited |
| Placer diggings | 9K | Very limited | Very limited | ||
| Maymen very rocky loam, 15 to 70 percent slopes | 9K | Excessively drained | D | Very limited | Very limited |
| Cohasset cobbly loam, 15 to 50 percent slopes | 8K | Well drained | B | Very limited | Very limited |
| Auburn extremely rocky silt loam, 3 to 70 percent slopes | 8K | Well drained | D | Very limited | Very limited |
| Holland very rocky coarse sandy loam, 15 to 50 percent slopes | 7K | Well drained | B | 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 88% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. 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.