San Diego County Area, California

Survey Area CA638• California

The dominant drainage class is Somewhat excessively 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 San Diego County 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
Acid igneous rock land	149K			Very limited	Very limited
Cieneba-Rock outcrop complex, 30 to 75 percent slopes, very stony	128K	Somewhat excessively drained	D	Very limited	Very limited
Cieneba-Fallbrook rocky sandy loams, 30 to 65 percent slopes, eroded	104K	Somewhat excessively drained	D	Very limited	Very limited
Sheephead sandy loam, 30 to 65 percent slopes, eroded, stony	91K	Well drained	D	Very limited	Very limited
Tollhouse coarse sandy loam, 30 to 70 percent slopes, very stony	86K	Somewhat excessively drained	D	Very limited	Very limited
Las Posas loam, 30 to 65 percent slopes, stony	55K	Well drained	D	Very limited	Very limited
San Miguel-Exchequer rocky silt loams, 9 to 70 percent slopes	45K	Well drained	D	Very limited	Very limited
Fallbrook sandy loam, 9 to 15 percent slopes, eroded	37K	Well drained	C	Somewhat limited	Very limited
Tollhouse coarse sandy loam, 5 to 35 percent slopes, eroded, very stony	36K	Somewhat excessively drained	D	Very limited	Very limited
Cieneba rocky coarse sandy loam, 9 to 30 percent slopes, eroded	32K	Somewhat excessively drained	D	Very limited	Very limited
La Posta loamy coarse sand, 5 to 30 percent slopes, eroded	30K	Somewhat excessively drained	A	Very limited	Very limited
La Posta rocky loamy coarse sand, 5 to 30 percent slopes, eroded	30K	Somewhat excessively drained	A	Very limited	Very limited
Mottsville loamy coarse sand, 2 to 9 percent slopes	30K	Excessively drained	A	Not limited	Very limited
Friant rocky fine sandy loam, 30 to 70 percent slopes	30K	Well drained	D	Very limited	Very limited
Carrizo very gravelly sand, 0 to 9 percent slopes	28K	Excessively drained	A	Very limited	Very limited
Redding cobbly loam, dissected, 15 to 50 percent slopes	28K	Well drained	D	Very limited	Very limited
Metamorphic rock land	26K	Excessively drained		Very limited	Very limited
Fallbrook sandy loam, 15 to 30 percent slopes, eroded	25K	Well drained	C	Very limited	Very limited
Water	25K		D	Not rated	Not rated
Bancas stony loam, 30 to 65 percent slopes	24K	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.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

Vertisols

High-clay soils that shrink and swell dramatically. Fertile but challenging for foundations and septic systems.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

What This Means

Building & Foundations

About 91% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas, sandy or gravelly soils with low bearing capacity. A geotechnical assessment is recommended before building.

Septic Systems

About 97% of soils are rated "very limited" for septic absorption fields. The well-drained soils may actually drain too fast for standard leach fields, allowing effluent to reach groundwater. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

Gardening & Agriculture

Soils tend to drain very quickly, meaning nutrients and water don't stick around long. Raised beds with amended soil, drip irrigation, and heavy mulching will give the best results. Compost is your best friend here — it improves water retention dramatically.