Soil survey area

Seward Peninsula and Nulato Hills Area, Alaska

Survey Area AK733• Alaska

The short version

The most common soil here is E40-maritime tussock-scrub-silty frozen slopes, on about 9% of the land. E41-arctic tussock-scrub-silty frozen slopes and E41-arctic tussock-gravelly frozen slopes come next.

About 8% of the land drains well, and 67% stays wet for long stretches; groundwater comes within two feet of the surface under 76% 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: 20% of the land floods occasionally or more, and bedrock lies within 40 inches under 28% 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 Very poorly drained and the dominant hydrologic group is B/D (varies with drainage). 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 Seward Peninsula and Nulato Hills 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
Seward Peninsula Highlands-Arctic Upland-Loess Plains	1.4M	Very poorly drained	B/D	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Water, Saline	1.4M			Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Upland-Rounded Mountains, Acid	1.3M	Very poorly drained	C	Very limited	Very limited
Seward Peninsula Highlands-Arctic Upland-Hills and Plains, Gravelly	1.1M	Very poorly drained	D	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Upland-Plains and Hills, Silty	998K	Very poorly drained	B/D	Very limited	Very limited
Seward Peninsula Highlands-Arctic Upland-Rounded Mountains, Calcareous	726K			Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Boreal Upland and Maritime Upland-Glaciated Mountains	377K	Poorly drained	D	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Upland-Rounded Mountains	261K	Well drained	A	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Lowland-Coastal Plains	217K	Very poorly drained	B/D	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Upland-Plains and Hills, Gravelly	207K	Very poorly drained	D	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Boreal Upland and Maritime Upland-Rounded Mountains	193K	Well drained	B	Very limited	Very limited
Seward Peninsula Highlands-Arctic Lowland-Flood Plains and Terraces	173K	Poorly drained	D	Very limited	Very limited
Seward Peninsula Highlands-Arctic Upland-Rounded Mountains, Acid	171K	Moderately well drained	C	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Maritime Lowland-Flood Plains and Terraces	159K	Somewhat poorly drained	B/D	Very limited	Very limited
Northern Seward Peninsula-Selawik Lowlands-Arctic Uplands-Plains, Silty	156K	Very poorly drained	B/D	Very limited	Very limited
Seward Peninsula Highlands-Arctic Upland-Rounded Mountains	107K	Well drained	B	Very limited	Very limited
Nulato Hills-Southern Seward Peninsula Highlands-Boreal Upland and Maritime Upland-Rounded Mountains, Acid	105K	Well drained	C	Very limited	Very limited
Northern Seward Peninsula-Selawik Lowlands-Water, Saline	97K			Very limited	Very limited
Yukon-Kuskokwim Coastal Plain-Maritime Lowland-Plains	92K	Well drained	D	Very limited	Very limited
Seward Peninsula Highlands-Arctic Upland-Coastal Plains	81K	Very poorly drained	C/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.

Entisols

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

Mollisols

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

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.