San Luis Obispo County, California, Coastal Part
The most common soil here is Lodo, on about 8% of the land: a shaly clay loam, firm and a little sticky. Los Osos and Diablo come next.
About 83% of the land drains well.
USDA rates 98% of the land very limited for a standard septic drain field, and 85% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 3% of the land floods occasionally or more, and bedrock lies within 40 inches under 71% 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 Luis Obispo County, California, Coastal Part, 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 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 Luis Obispo County, California, Coastal Part. 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 |
|---|---|---|---|---|---|
| Rock outcrop-Lithic Haploxerolls complex, 30 to 75 percent slopes | 29K | D | Very limited | Very limited | |
| Santa Lucia channery clay loam, 50 to 75 percent slopes, MLRA 15 | 25K | Well drained | C | Very limited | Very limited |
| Lopez very shaly clay loam, 30 to 75 percent slopes | 25K | Somewhat excessively drained | D | Very limited | Very limited |
| Lompico-McMullin loams, 30 to 75 percent slopes | 20K | Well drained | C | Very limited | Very limited |
| Los Osos-Lodo complex, 30 to 75 percent slopes | 20K | Well drained | D | Very limited | Very limited |
| Diablo-Lodo complex, 15 to 50 percent slopes | 18K | Well drained | C | Very limited | Very limited |
| Gazos-Lodo clay loams, 30 to 50 percent slopes | 15K | Well drained | C | Very limited | Very limited |
| Diablo and Cibo clays, 30 to 50 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Oceano sand, 0 to 9 percent slopes | 14K | Excessively drained | A | Not limited | Very limited |
| Diablo and Cibo clays, 15 to 30 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Dune land | 13K | Excessively drained | Very limited | Very limited | |
| Los Osos-Diablo complex, 30 to 50 percent slopes | 12K | Well drained | D | Very limited | Very limited |
| Obispo-Rock outcrop complex, 15 to 75 percent slopes | 12K | Well drained | D | Very limited | Very limited |
| Henneke-Rock outcrop complex, 15 to 75 percent slopes | 11K | D | Very limited | Very limited | |
| Santa Lucia channery clay loam, 30 to 50 percent slopes, MLRA 15 | 10K | Well drained | D | Very limited | Very limited |
| Gaviota fine sandy loam, 15 to 50 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Los Osos loam, 30 to 50 percent slopes | 10K | Well drained | D | Very limited | Very limited |
| Cropley clay, 2 to 9 percent slopes, MLRA 14 | 10K | Moderately well drained | C | Very limited | Very limited |
| Lodo-Rock outcrop complex, 30 to 75 percent slopes | 9K | Somewhat excessively drained | D | Very limited | Very limited |
| Corducci and Typic Xerofluvents, 0 to 5 percent slopes, occasionally flooded, MLRA 14 | 8K | Somewhat excessively drained | A | 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 85% 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 98% 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.