Soil survey area

Brooks Range - Kobuk Valley National Park and Noatak Preserve Area, Alaska

Survey Area AK753• Alaska

The short version

The most common soil here is E43-Arctic scrub-sedge-gravelly frozen till slopes, on about 14% of the land. E43-Arctic dwarf scrub-gravelly colluvial slopes and E43-Arctic tussock-scrub-silty slopes, frozen come next.

About 16% of the land drains well, and 50% stays wet for long stretches; groundwater comes within two feet of the surface under 65% of it.

USDA rates all of the land very limited for a standard septic drain field, and all 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 7% 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 Brooks Range - Kobuk Valley National Park and Noatak 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
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Glaciated Valleys	2.3M	Poorly drained	D	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Rugged Mountains	1.5M			Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine and Upland-Plains and Hills	1.3M	Very poorly drained	C/D	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Rounded Mountains	1.1M			Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Rugged Mountains, Calcareous	573K	Well drained	B	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine Rugged Mountains, Acid	566K	Well drained	B	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Upland and Lowland-Glaciated Valleys	281K	Poorly drained	D	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Lowland-Flood Plains and Terraces	266K	Very poorly drained	B/D	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Rolling Mountains, Calcareous	244K			Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Upland-Lower Mountain Slopes	174K	Well drained	B	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine and Upland-Plains and Hills, Calcareous	31K	Well drained	B	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Boreal Alpine-Barren Mountains	27K			Very limited	Very limited
Northern Brooks Range Mountains-Arctic Upland-Rugged Mountains	7K	Well drained	B	Very limited	Very limited
Northern Brooks Range Mountains-Arctic Upland-Rounded Mountains	5K	Well drained	B	Very limited	Very limited
Western Brooks Range Mountains, Foothills, and Valleys-Water, Fresh	4K			Not limited	Not limited
Northern Brooks Range Mountains-Arctic Upland-Rugged Mountains, Calcareous	1K	Well drained	A	Very limited	Very limited
Northern Seward Peninsula-Selawik Lowlands-Arctic Lowland-Coastal Plains	1K	Very poorly drained	C/D	Very limited	Very limited
Northern Seward Peninsula-Selawik Lowlands-Arctic Lowland-Coastal Plains, Low	335	Very poorly drained	D	Very limited	Very limited
Northern Brooks Range Mountains-Arctic Upland and Lowland-Glaciated Valleys	29	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.

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.

Entisols

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

What This Means

Building & Foundations

About 100% 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 100% 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.