Soil survey area

Kootenai National Forest Area, Montana-Idaho

Survey Area MT634• Montana

The short version

The most common soil here is Andic Dystrochrepts, on about 36% of the land. Andic Cryochrepts and Phillcher come next.

About 89% of the land drains well; groundwater comes within two feet of the surface under 3% of it.

USDA rates 87% of the land very limited for a standard septic drain field, and 82% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: bedrock lies within 40 inches under 16% of it.

Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.

The ground underfoot

The soils you're most likely standing on

The biggest named soils in Kootenai National Forest Area, Montana-Idaho, each drawn five feet deep from its official USDA description, in its recorded colors.

Phillcher

8% of the area

Ashy silt loam topsoil · well drained

Smooth, like flour. Fertile and holds water well.

Inceptisols

Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.

The biggest mapped areas

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). 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 Kootenai National Forest Area, Montana-Idaho. 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
Andic Dystrochrepts, glaciated mountain slopes	475K	Well drained	B	Very limited	Very limited
Andic Dystrochrepts-Rock outcrop complex, glaciated mountain slopes	437K	Well drained	B	Very limited	Very limited
Phillcher-Rock outcrop complex, mountain slopes	102K	Well drained	B	Very limited	Very limited
Phillcher ashy silt loam, glaciated mountain ridges	100K	Well drained	B	Very limited	Very limited
Rock outcrop-Andic Cryochrepts-Lithic Cryochrepts complex, glacial trough walls	91K	Well drained	D	Very limited	Very limited
Lithic Cryochrepts-Andic Cryochrepts-Rock outcrop complex, glaciated mountain ridges	91K	Well drained	D	Very limited	Very limited
Andic Dystrochrepts, breaklands	76K	Well drained	B	Very limited	Very limited
Eutric Glossoboralfs, moraines	69K	Well drained	C	Very limited	Very limited
Phillcher-Rock Outcrop-Sig complex, dissected glaciated mountain slopes	69K	Well drained	B	Very limited	Very limited
Andic Dystric Eutrochrepts, lacustrine terraces-Andic Dystrochrepts, glacial outwash terraces, complex	60K	Moderately well drained	B	Not limited	Somewhat limited
Rock outcrop-Lithic Cryochrepts-Andic Cryochrepts complex, cirque headwalls and alpine ridges	60K		D	Not rated	Not rated
Andic Dystrochrepts, mountain slopes	58K	Well drained	B	Very limited	Very limited
Andic Cryochrepts-Rock outcrop-Lithic Cryochrepts complex, glaciated mountain ridges	58K	Well drained	D	Very limited	Very limited
Andic Dystric Eutrochrepts, lacustrine terraces	51K	Moderately well drained	B	Not limited	Somewhat limited
Andic Cryochrepts, moraines, steep	51K	Well drained	B	Very limited	Very limited
Andic Cryochrepts, moraines, dense, brittle substratum	50K	Well drained	B	Very limited	Very limited
Rock outcrop-Lithic Ustochrepts-Typic Ustochrepts complex, breaklands	46K	Well drained	D	Very limited	Very limited
Andic Cryochrepts, moraines	45K	Well drained	B	Very limited	Very limited
Typic Eutroboralfs, moraines	44K	Well drained	C	Very limited	Very limited
Typic Ustochrepts, glaciated mountain slopes, steep	40K	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.

Mollisols

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

Andisols

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

Alfisols

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

What This Means

Building & Foundations

About 82% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes. A geotechnical assessment is recommended before building.

Septic Systems

About 87% 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.