Alameda County, California, Western Part

Survey Area CA610• California

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 Alameda County, California, Western 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
Water	52K		D	Not rated	Not rated
Novato clay, ponded	17K	Very poorly drained	D	Very limited	Very limited
Danville silty clay loam, 0 to 2 percent slopes	12K	Well drained	C	Very limited	Very limited
Urban land	11K		D	Not rated	Not rated
Clear Lake clay, drained, 0 to 2 percent slopes, MLRA 14	9K	Poorly drained	D	Very limited	Very limited
Yolo silt loam, 0 to 3 percent slopes, dry, MLRA 14	6K	Well drained	B	Not limited	Somewhat limited
Botella loam, 0 to 2 percent slopes, MLRA 14	5K	Well drained	C	Not limited	Very limited
Urban land-Tierra complex, 2 to 5 percent slopes	5K	Moderately well drained	D	Somewhat limited	Very limited
Sycamore silt loam, drained, 0 to 2 percent slopes, MLRA 14	5K	Poorly drained	B	Not limited	Somewhat limited
Xeropsamments, fill	5K		A	Somewhat limited	Very limited
Urban land-Clear Lake complex	4K		D	Not rated	Not rated
Urban land-Baywood complex	4K		D	Not rated	Not rated
Omni silty clay loam, drained	4K	Poorly drained	C	Very limited	Very limited
Reyes clay, 0 to 2 percent slopes	4K	Somewhat poorly drained	D	Very limited	Very limited
Novato clay, tidally flooded	4K	Very poorly drained	C/D	Very limited	Very limited
Marvin silt loam, saline-alkali	3K	Somewhat poorly drained	C	Very limited	Very limited
Xerorthents-Los Osos complex, 30 to 50 percent slopes	3K			Not rated	Not rated
Xerorthents-Millsholm complex, 30 to 50 percent slopes	3K		B	Very limited	Very limited
Maymen loam, 30 to 75 percent slopes	3K	Somewhat excessively drained	D	Very limited	Very limited
Urban land-Danville complex	3K		D	Not rated	Not rated

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.

Vertisols

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

Alfisols

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

Entisols

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

Inceptisols

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

What This Means

Building & Foundations

About 36% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.

Septic Systems

About 45% of soils have significant septic limitations, while others are more suitable. A perc test is essential — conditions vary across the area.

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.