Katmai National Park and Preserve Area, Alaska

Survey Area AK717• Alaska

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Andisols — soils formed in volcanic ash, very light and porous. 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 Katmai 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
Southern Alaska Peninsula Mountains-Maritime Upland-Rounded Mountains	1.5M	Well drained	B	Very limited	Very limited
Southern Alaska Peninsula Mountains-Maritime Alpine-Barren Mountains	570K			Very limited	Very limited
Bristol Bay-Northern Alaska Peninsula Lowlands-Boreal and Northwest Maritimel-Glaciated Plains, Ash Influenced	463K	Well drained	A	Not limited	Very limited
Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland-Glaciated Plains, Ash Influenced	343K	Very poorly drained	B	Very limited	Very limited
Southern Alaska Peninsula Mountains-Maritime Water, Saline	284K			Not rated	Not rated
Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Water, Fresh	275K			Not limited	Not limited
Southern Alaska Peninsula Mountains-Maritime Upland-Glaciated Plains and Hills	272K	Well drained	B	Very limited	Very limited
Southern Alaska Peninsula Mountains-Maritime Upland-Mountains	206K	Well drained	B	Very limited	Very limited
Southern Alaska Peninsula Mountains-Maritime Lowland-Flood Plains and Stream Terraces	119K	Well drained	B	Very limited	Very limited
Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland and Boreal Upland-Glaciated Rounded Mountains	31K	Poorly drained	A/D	Very limited	Very limited
Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland-Glaciated Rounded Mountains	16K	Well drained	A/D	Very limited	Very limited
Southern Alaska Peninsula Mountains-Maritime Lowland-Coastal Plains	4K	Very 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.

Andisols

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

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.

Spodosols

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

Gelisols

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

What This Means

Building & Foundations

About 74% 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 86% 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.