Lewis County Area, Washington

Survey Area WA641• Washington

The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). 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 Lewis County Area, 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
Buckpeak silt loam, 30 to 65 percent slopes	58K	Well drained	B	Very limited	Very limited
Prather silty clay loam, 0 to 5 percent slopes	44K	Moderately well drained	C	Very limited	Very limited
Lacamas silt loam, 0 to 3 percent slopes	40K	Poorly drained	C/D	Very limited	Very limited
Melbourne loam, 15 to 30 percent slopes	39K	Well drained	C	Very limited	Very limited
Pheeney gravelly loam, 30 to 65 percent slopes	28K	Well drained	C	Very limited	Very limited
Melbourne loam, 8 to 15 percent slopes	27K	Well drained	C	Somewhat limited	Very limited
Salkum silty clay loam, 0 to 5 percent slopes	26K	Well drained	C	Not limited	Very limited
Reed silty clay loam	24K	Poorly drained	D	Very limited	Very limited
Cinebar silt loam, 8 to 15 percent slopes	21K	Well drained	B	Somewhat limited	Somewhat limited
Centralia loam, 15 to 30 percent slopes	20K	Well drained	B	Very limited	Very limited
Water	19K			Not rated	Not rated
Cattcreek very cindery loamy sand, 30 to 65 percent slopes	19K	Well drained	B	Very limited	Very limited
Katula very cobbly loam, 30 to 65 percent slopes	18K	Well drained	C	Very limited	Very limited
Salkum silty clay loam, 5 to 15 percent slopes	18K	Well drained	C	Somewhat limited	Very limited
Galvin silt loam, 0 to 8 percent slopes	18K	Somewhat poorly drained	C/D	Very limited	Very limited
Cinebar silt loam, 0 to 8 percent slopes	18K	Well drained	B	Not limited	Somewhat limited
Salkum silty clay loam, 15 to 30 percent slopes	16K	Well drained	C	Very limited	Very limited
Pheeney-Rock outcrop complex, 65 to 90 percent slopes	16K	Well drained	C	Very limited	Very limited
Cinebar silt loam, 15 to 30 percent slopes	14K	Well drained	B	Very limited	Very limited
Baumgard loam, 30 to 65 percent slopes	14K	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.

Alfisols

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

What This Means

Building & Foundations

About 73% 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 88% 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.