County soil summary
Soil types in Anchorage Municipality, Alaska
The most widespread soils are Deception, Talkeetna and Kichatna; the most common drainage class is well drained (44% of the land), and typical topsoil pH is 5.5.
About 1.3 million acres of Anchorage Municipality lie in multi-county soil survey areas (AK770, AK771) that the soil survey does not split by county. Those acres, often public forest or desert land, are counted in the Alaska totals but not in the figures below.
- Well or moderately well drained
- 49% of land · state 35%
- Typical topsoil pH
- 5.5 strongly acidic · state 4.8
- Septic fields very limited
- 80% of land · state 88%
- Subject to flooding
- 28% of land, any frequency · state 12%
Most common soils in Anchorage Municipality
Share of mapped land
A county is a patchwork of many soils. These 8 cover 45% of the mapped land; 29 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| E23-boreal rock outcrop and rubblelandLand type, not a soil series | 14.3% | — | — |
| E22-maritime glaciers and permanent snowfieldsLand type, not a soil series | 5.9% | — | — |
| E24-boreal water, salineLand type, not a soil series | 5.7% | — | — |
| E23-boreal subalpine scrub/meadow mosaic-silty till slopesGeneral soil group, not a named series | 5.0% | — | — |
| Deception | 4.2% | Well drained | 5.0 |
| Talkeetna | 3.6% | Well drained | 4.3 |
| Kichatna | 3.4% | Well drained | 5.0 |
| CryorthentsGeneral soil group, not a named series | 3.2% | — | — |
What this means
What the soils in Anchorage Municipality mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Anchorage Municipality is strongly acidic: pH 5.5 (most land between 4.4 and 6.3). Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.
Loamy topsoil (loam, silt loam and similar) covers 53% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (33% of the land).
For your lawn and yard
Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.
For a septic system
For conventional septic absorption fields, NRCS rates 80% of the land in Anchorage Municipality very limited, 6% somewhat limited and 0% not limited (14% not rated, such as urban land, pits or water).
Statewide, 88% of the land is very limited, so Anchorage Municipality is less restrictive than typical.
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Flooding is mapped on 28% of the land (1% occasional, 27% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Drainage
How long the soil stays wet
The most common drainage class is well drained (44%). 49% of the land is moderately well drained or better, compared with 35% across Alaska.
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| Excessively drained | 0.4% | 0.2% |
| Somewhat excessively drained | 3.7% | 1.7% |
| Well drained | 43.6% | 29.6% |
| Moderately well drained | 1.1% | 3.6% |
| Somewhat poorly drained | 2.0% | 6.1% |
| Poorly drained | 3.9% | 18.2% |
| Very poorly drained | 9.5% | 19.4% |
| Not rated | 35.9% | 21.1% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| Not limited | 0.0% | 4.3% |
| Somewhat limited | 6.4% | 2.5% |
| Very limited | 80.1% | 88.4% |
| Not rated | 13.5% | 4.8% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 9.9% | 8.0% |
| B: moderate infiltration | 33.8% | 18.5% |
| C: slow infiltration | 3.2% | 5.4% |
| D: very slow infiltration (clayey, shallow or wet) | 11.7% | 23.9% |
| A/D: D as is, A if drained | 2.8% | 3.9% |
| B/D: D as is, B if drained | 2.5% | 12.4% |
| C/D: D as is, C if drained | 0.1% | 6.6% |
| Not rated | 36.0% | 21.2% |
Flooding
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| No flooding | 66.0% | 76.2% |
| Rare or very rare | 0.5% | 1.4% |
| Occasional | 1.4% | 2.7% |
| Frequent or very frequent | 26.5% | 7.7% |
| Not reported | 5.6% | 12.0% |
Seasonal high water table
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| Within 18 inches at some time of year | 14.7% | 43.5% |
| 18 inches to 3.3 feet | 1.9% | 4.2% |
| Deeper than 3.3 feet or none reported | 77.8% | 40.6% |
| Not reported | 5.6% | 11.7% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 5.5 (strongly acidic); 80% of rated land falls between 4.4 and 6.3. Median topsoil organic matter is 6%.
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| Strongly acidic (below 5.5) | 29.1% | 45.5% |
| Moderately to slightly acidic (5.5–6.4) | 29.9% | 13.4% |
| Near neutral (6.5–7.3) | 1.2% | 4.4% |
| Alkaline (7.4 and up) | 2.1% | 2.8% |
| Not reported | 37.8% | 33.9% |
Texture
Show as a table
| Category | Anchorage Municipality | Alaska |
|---|---|---|
| Sandy | 1.7% | 1.6% |
| Loamy (loam, silt loam and similar) | 52.8% | 42.3% |
| Clayey (40%+ clay) | 0.0% | 0.0% |
| Organic (muck or peat) | 9.7% | 33.9% |
| Not reported (rock, urban land, etc.) | 35.8% | 22.3% |
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- Anchorage Municipality, Alaska (FIPS 02020): 574,933 acres of mapped land, 12,510 acres of open water excluded. State comparisons pool all mapped land in Alaska.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.