Soil survey area

Denali National Park and Preserve Area, Alaska

Survey Area AK651• Alaska

The short version

The most common soil here is Alpine-dwarf scrub gravelly colluvial slopes, on about 5% of the land. Boreal-taiga silty loess slopes and Boreal-taiga/tussock silty loess slopes come next.

About 30% of the land drains well, and 37% stays wet for long stretches; groundwater comes within two feet of the surface under 54% of it.

USDA rates 99% of the land very limited for a standard septic drain field, and 97% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: 4% of the land floods occasionally or more, and bedrock lies within 40 inches under 48% 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 biggest mapped areas

The dominant drainage class is Poorly drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Gelisols — permafrost soils found in very cold climates. 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 Denali National Park and Preserve Area, Alaska. 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
Nonvegetated Mountains, South Central Mountains	1.1M			Very limited	Very limited
Nonvegetated Mountains, Alaska Mountains	714K			Very limited	Very limited
Boreal Loess Plains, Hills, and Drains with Continuous Permafrost	145K	Poorly drained	D	Very limited	Very limited
Boreal Loess Plains and Peat Plateaus with Continuous Permafrost	143K	Poorly drained	D	Very limited	Very limited
Boreal Terraces with Discontinuous Permafrost	136K	Poorly drained	D	Very limited	Very limited
Boreal Loess Plains with Continuous Permafrost	124K	Poorly drained	C/D	Very limited	Very limited
Alpine Till Plains and Hills with Discontinuous Permafrost	116K	Well drained	A	Very limited	Very limited
Alpine Mountains	112K	Well drained	B	Very limited	Very limited
Alpine Dark Sedimentary Mountains, High Elevation	109K	Well drained	C	Very limited	Very limited
Boreal Loess Plains and Hills with Continuous Permafrost	105K	Poorly drained	D	Very limited	Very limited
Alpine Schist Mountains with Discontinuous Permafrost	93K	Well drained	C	Very limited	Very limited
Boreal Terraces with Continuous Permafrost, Very Wet	91K	Poorly drained	C/D	Very limited	Very limited
Alpine Mixed Lithology Mountains, High Elevation	87K	Well drained	B	Very limited	Very limited
Alpine Till Plains with Discontinuous Permafrost	86K	Poorly drained	D	Very limited	Very limited
Boreal Terraces with Continuous Permafrost	85K	Poorly drained	D	Very limited	Very limited
Boreal Eolian Plains and Dunes with Discontinuous Permafrost	79K	Poorly drained	D	Very limited	Very limited
Boreal Groundwater Discharge Plains with Discontinuous Permafrost	74K	Poorly drained	A/D	Very limited	Very limited
Boreal Flood Plains with Discontinuous Permafrost	70K	Well drained	B	Very limited	Very limited
Boreal and Subalpine Schist Mountain Valleys	69K	Poorly drained	B/D	Very limited	Very limited
Boreal Terraces and High Flood Plains with Continuous Permafrost	69K	Poorly drained	D	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.

Gelisols

Permafrost soils. Extremely challenging for construction and septic. Found almost exclusively in Alaska.

Spodosols

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

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Inceptisols

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

What This Means

Building & Foundations

About 97% 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 99% of soils are rated "very limited" for septic absorption fields. Poorly drained soils can't absorb septic effluent effectively. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

Gardening & Agriculture

Many soils hold water for extended periods. Raised beds are highly recommended to improve drainage for vegetables. Well-adapted native plants and water-loving species will do best in natural conditions.