Clark County, Washington

Survey Area WA011• Washington

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Andisols — soils formed in volcanic ash, very light and porous. 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 Clark County, Washington. 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
Hesson clay loam, 0 to 8 percent slopes	24K	Well drained	C	Somewhat limited	Very limited
Cinebar silt loam, 8 to 20 percent slopes	23K	Well drained	B	Somewhat limited	Somewhat limited
Cinebar stony silt loam, 30 to 70 percent slopes	21K	Well drained	B	Very limited	Very limited
Cinebar silt loam, 20 to 30 percent slopes	20K	Well drained	B	Very limited	Very limited
Olympic clay loam, 8 to 20 percent slopes	18K	Well drained	C	Somewhat limited	Very limited
Gee silt loam, 0 to 8 percent slopes	16K	Moderately well drained	C	Somewhat limited	Very limited
Kinney silt loam, 30 to 50 percent slopes	13K	Well drained	B	Very limited	Very limited
Olympic stony clay loam, 3 to 30 percent slopes	12K	Well drained	C	Very limited	Very limited
Olympic stony clay loam, 30 to 60 percent slopes	11K	Well drained	C	Very limited	Very limited
Lauren gravelly loam, 0 to 8 percent slopes	11K	Well drained	B	Not limited	Very limited
Cinebar silt loam, 30 to 70 percent slopes	11K	Well drained	B	Very limited	Very limited
Dollar loam, 0 to 5 percent slopes	11K	Moderately well drained	C	Very limited	Very limited
Hesson clay loam, 8 to 20 percent slopes	11K	Well drained	C	Somewhat limited	Very limited
Olympic clay loam, 30 to 60 percent slopes	10K	Well drained	C	Very limited	Very limited
Hillsboro loam, 3 to 8 percent slopes	9K	Well drained	B	Not limited	Very limited
Hillsboro silt loam, 0 to 3 percent slopes	8K	Well drained	B	Not limited	Somewhat limited
Hillsboro silt loam, 3 to 8 percent slopes	8K	Well drained	B	Not limited	Somewhat limited
Odne silt loam, 0 to 5 percent slopes	7K	Poorly drained	D	Very limited	Very limited
Hillsboro loam, 0 to 3 percent slopes	7K	Well drained	B	Not limited	Very limited
Cinebar stony silt loam, 3 to 30 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.

Andisols

Volcanic ash soils — light, porous, and fertile. Excellent drainage, but low density can complicate foundations.

Mollisols

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

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.

Alfisols

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

What This Means

Building & Foundations

About 47% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.

Septic Systems

About 85% 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.