Sonoma County, California

Survey Area CA097• California

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). 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 Sonoma County, 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 very gravelly loam, 50 to 75 percent slopes	90K	Well drained	B	Very limited	Very limited
Hugo-Josephine complex, 50 to 75 percent slopes	34K	Well drained	B	Very limited	Very limited
Laughlin loam, 50 to 75 percent slopes	26K	Well drained	C	Very limited	Very limited
Hugo loam, 30 to 50 percent slopes	24K	Well drained	B	Very limited	Very limited
Reyes clay, 0 to 2 percent slopes	24K	Somewhat poorly drained	C	Very limited	Very limited
Los Gatos loam, 30 to 75 percent slopes, MLRA 15	23K	Well drained	C	Very limited	Very limited
Josephine loam, 30 to 50 percent slopes	23K	Well drained	B	Very limited	Very limited
Laughlin loam, 30 to 50 percent slopes	21K	Well drained	C	Very limited	Very limited
Rock land	19K	Excessively drained		Very limited	Very limited
Clear Lake clay, sandy substratum, 0 to 2 percent slopes	19K	Poorly drained	C/D	Very limited	Very limited
Water	17K		D	Not rated	Not rated
Josephine loam,50 to 75 percent slopes	17K	Well drained	C	Very limited	Very limited
Suther loam, 30 to 50 percent slopes	14K	Moderately well drained	D	Very limited	Very limited
Stonyford gravelly loam, 50 to 75 percent slopes, eroded	14K	Well drained	D	Very limited	Very limited
Yorkville clay loam, 30 to 50 percent slopes	14K	Moderately well drained	D	Very limited	Very limited
Yorkville-Laughlin complex, 30 to 50 percent slopes	13K	Moderately well drained	D	Very limited	Very limited
Goulding clay loam, 30 to 50 percent slopes	13K	Well drained	D	Very limited	Very limited
Goldridge fine sandy loam, 15 to 30 percent slopes	12K	Moderately well drained	C	Very limited	Very limited
Henneke gravelly loam, 30 to 75 percent slopes, eroded	12K	Well drained	D	Very limited	Very limited
Maymen gravelly sandy loam, 30 to 50 percent slopes	12K	Well drained	D	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.

Mollisols

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

Alfisols

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

Ultisols

Strongly weathered clay soils of the Southeast. Acidic and naturally low in nutrients. Clay subsoil can slow drainage.

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.

Vertisols

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

What This Means

Building & Foundations

About 96% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 96% 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.