Alaska Peninsula - Aniakchak and Unimak Area, Alaska
The most common soil here is E25-Maritime tall scrub-sandy volcanic slopes, on about 10% of the land. E25-Maritime tall scrub-ashy till slopes and E25-Maritime dwarf scrub-gravelly volcanic colluvial slopes come next.
About 43% of the land drains well, and 8% stays wet for long stretches; groundwater comes within two feet of the surface under 25% of it.
USDA rates 60% of the land very limited for a standard septic drain field, and 50% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 39% of the land floods occasionally or more, and 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 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 Alaska Peninsula - Aniakchak and Unimak 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 Water, Saline | 3.0M | Not rated | Not rated | ||
| Southern Alaska Peninsula Mountains-Maritime Upland-Mountains | 1.1M | Well drained | B | Very limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Upland-Rounded Mountains | 1.1M | Well drained | B | Very limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Alpine-Barren Mountains | 735K | Very limited | Very limited | ||
| Southern Alaska Peninsula Mountains-Maritime Upland-Volcanic Mountains and Lowland-Flood Plains and Stream Terraces | 706K | Somewhat excessively drained | B | Not limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Upland-Glaciated Plains and Hills | 522K | Well drained | B | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland-Glaciated Plains, Ash Influenced | 431K | Very poorly drained | B | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Water, Fresh | 250K | Not limited | Not limited | ||
| Southern Alaska Peninsula Mountains-Maritime Upland-Glaciated Plains, Hummocky | 173K | Well drained | B | Somewhat limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Lowland-Coastal Plains | 144K | Very poorly drained | D | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland-Glaciated Plains and Peatlands | 64K | Very poorly drained | B/D | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Lowlands-Coastal Plains, Low | 56K | Very poorly drained | B/D | Very limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Upland-Southern Kodiak Hills and Plains | 21K | Well drained | B | Not limited | Somewhat limited |
| Southern Alaska Peninsula Mountains-Maritime Water, Fresh | 18K | Not rated | Not rated | ||
| Southern Alaska Peninsula Mountains-Maritime Upland-Glaciated Plains and Hills, Wet | 14K | Well drained | A | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Boreal Lowland-Flood Plains and Terraces | 10K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Bristol Bay-Northern Alaska Peninsula Lowlands-Boreal and Northwest Maritimel-Glaciated Plains, Ash Influenced | 4K | Well drained | A | Not limited | Very limited |
| Southern Alaska Peninsula Mountains-Maritime Upland-Southern Kodiak Mountains | 2K | Well drained | B | 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.
What This Means
Building & Foundations
About 50% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 60% 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.