Marion County Area, Oregon

Survey Area OR643• Oregon

The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Inceptisols — young soils with minimal horizon development but more than Entisols. 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 Marion County Area, Oregon. 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
Woodburn silt loam, 0 to 3 percent slopes	64K	Moderately well drained	C	Very limited	Very limited
Amity silt loam	50K	Somewhat poorly drained	C/D	Very limited	Very limited
Nekia silty clay loam, 2 to 7 percent slopes	24K	Well drained	C	Very limited	Very limited
Kinney cobbly loam, 20 to 50 percent slopes	23K	Well drained	B	Very limited	Very limited
McCully clay loam, 30 to 50 percent slopes	18K	Well drained	C	Very limited	Very limited
Cloquato silt loam	18K	Well drained	B	Very limited	Very limited
Nekia silty clay loam, 7 to 12 percent slopes	16K	Well drained	C	Very limited	Very limited
Concord silt loam	14K	Poorly drained	C/D	Very limited	Very limited
Nekia silty clay loam, 12 to 20 percent slopes	14K	Well drained	C	Very limited	Very limited
Kinney cobbly loam, 2 to 20 percent slopes	12K	Well drained	B	Somewhat limited	Somewhat limited
Dayton silt loam	12K	Poorly drained	D	Very limited	Very limited
Jory silty clay loam, 2 to 7 percent slopes	12K	Well drained	C	Somewhat limited	Very limited
Wapato silty clay loam	12K	Poorly drained	C/D	Very limited	Very limited
Clackamas gravelly loam	11K	Somewhat poorly drained	C/D	Very limited	Very limited
Henline extremely stony sandy loam, 55 to 80 percent slopes	10K	Well drained	B	Very limited	Very limited
Woodburn silt loam, 3 to 12 percent slopes	8K	Moderately well drained	C	Very limited	Very limited
Jory silty clay loam, 7 to 12 percent slopes	8K	Well drained	C	Somewhat limited	Very limited
McCully clay loam, 50 to 70 percent slopes	8K	Well drained	C	Very limited	Very limited
Willamette silt loam, 0 to 3 percent slopes	8K	Well drained	B	Somewhat limited	Somewhat limited
McAlpin silty clay loam, 0 to 3 percent slopes	7K	Moderately well drained	C	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.

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.

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.

Spodosols

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

Andisols

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

What This Means

Building & Foundations

About 88% 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 94% 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.