Cowlitz County, Washington

Survey Area WA015• 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 Cowlitz 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
Olympic silt loam, 8 to 20 percent slopes	40K	Well drained	B	Somewhat limited	Somewhat limited
Hazeldell gravelly silt loam, 30 to 65 percent slopes	34K	Well drained	B	Very limited	Very limited
Hazeldell gravelly silt loam, 20 to 30 percent slopes	28K	Well drained	B	Very limited	Very limited
Olympic silt loam, 20 to 30 percent slopes	20K	Well drained	B	Very limited	Very limited
Pheeney-Beigle complex, 30 to 65 percent slopes	20K	Well drained	C	Very limited	Very limited
Hazeldell gravelly silt loam, tuff substratum, 30 to 65 percent slopes	19K	Well drained	C	Very limited	Very limited
Gobar silt loam, 30 to 65 percent slopes	19K	Well drained	B	Very limited	Very limited
Centralia silt loam, 20 to 30 percent slopes	18K	Well drained	B	Very limited	Very limited
Olympic silt loam, tuff substratum, 5 to 30 percent slopes	17K	Well drained	B	Very limited	Very limited
Cinebar silt loam, 5 to 20 percent slopes	13K	Well drained	B	Somewhat limited	Somewhat limited
Caples silty clay loam, 0 to 3 percent slopes	13K	Somewhat poorly drained	C/D	Very limited	Very limited
Baumgard silt loam, 30 to 65 percent slopes	11K	Well drained	B	Very limited	Very limited
Hazeldell gravelly silt loam, 8 to 20 percent slopes	11K	Well drained	B	Somewhat limited	Somewhat limited
Pheeney-Beigle complex, 5 to 30 percent slopes	11K	Well drained	C	Very limited	Very limited
Germany silt loam, 20 to 30 percent slopes	10K	Well drained	B	Very limited	Very limited
Water	10K			Not rated	Not rated
Swift sandy loam, 30 to 65 percent slopes	8K	Well drained	B	Very limited	Very limited
Buckpeak silt loam, 30 to 65 percent slopes	8K	Well drained	B	Very limited	Very limited
Mulholland silt loam, 5 to 30 percent slopes	8K	Well drained	B	Very limited	Very limited
Vanson-Hatchet complex, 30 to 65 percent slopes	8K	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.

Spodosols

Acidic forest soils with a leached layer. Common under conifers. Often have drainage issues from a compacted subsoil layer.

Inceptisols

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

Ultisols

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

What This Means

Building & Foundations

About 77% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 77% 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.