Soil series profile

Dunstone soil series

Dunstone is a well drained soil with a silt loam surface, mapped on 47,119 acres in 8 counties in CA. Hydrologic group D.

#6205 by mapped area loamy Ultic Haploxeralfs (Alfisols)

Drainage class
Well drained
99% of mapped acres
Hydrologic group
D
99% of mapped acres
Typical topsoil pH
6.0
moderately acidic · range 5.0–6.1
Mapped area
47k
acres in 8 counties, 1 state

Typical Dunstone profile

Texture and pH by depth

Typical Dunstone soil profile by depth 0 in 10 in 20 in 0–3 in · A · pH 6.1 · 13% clay Silt loam 3–7 in · Bt1 · pH 6.1 · 16% clay Silt loam 7–12 in · Bt2 · pH 6.1 · 21% clay Loam 12–22 in · Cr Bedrock
Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).
Show as a table
Typical Dunstone horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–3 in (A) Silt loam 6.1 13% 35% 3.5%
3–7 in (Bt1) Silt loam 6.1 16% 32% 1%
7–12 in (Bt2) Loam 6.1 21% 30% 1%
12–22 in (Cr) Bedrock Not reported Not reported Not reported Not reported

Representative values from the most extensive Dunstone map unit (Aquic Haploxeralfs, rarely flooded and occasionally ponded-Loafercreek-Dunstone complex, 1 to 12 percent slopes, survey area CA630). Other map units of this series vary within the series range.

Hands holding dark garden soil
Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Dunstone soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Dunstone soils is moderately acidic: pH 6.0 (most land between 5.0 and 6.1). Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.

Loamy topsoil (loam, silt loam and similar) covers 99% of mapped Dunstone acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is gravelly loam (43% of mapped Dunstone acres).

99% of mapped Dunstone acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 99% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

For a septic system

For conventional septic absorption fields, NRCS rates 99% of the acres in mapped Dunstone soils very limited, 0% somewhat limited and 0% not limited (1% not rated, such as urban land, pits or water).

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.

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Dunstone soil is found

Mapped acres

Dunstone is mapped in California.

Counties with the most mapped Dunstone soil
County Acres Share of county land
Butte County, CA 35,622 2.6%
Calaveras County, CA 4,520 0.4%
Tuolumne County, CA 4,520 0.2%
Mariposa County, CA 1,969 0.2%
Yuba County, CA 359 0.1%
Stanislaus County, CA 63 0.0%
Amador County, CA 31 0.0%
Nevada County, CA 10 0.0%

Septic absorption fields

NRCS rating, share of Dunstone acres

Not limited 0%
Somewhat limited 0%
Very limited 99%
Not rated 1%
Septic tank absorption field rating across mapped Dunstone acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Dunstone acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited98.7%
Not rated1.3%

Drainage, water table and flooding

Share of Dunstone acres

Depth to seasonal high water table
None reported within about 6.5 feet (median where reported).
Flooding
Not mapped as flooding on most acres.
Slope
Typically 1–70% (median 8%).
Topsoil organic matter
Median 6%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 99%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 0%
Very poorly drained 0%
Not rated 1%
Drainage class across mapped Dunstone acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Dunstone acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained98.7%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained0.0%
Very poorly drained0.0%
Not rated1.3%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 0%
C: slow infiltration 0%
D: very slow infiltration (clayey, shallow or wet) 99%
A/D: D as is, A if drained 0%
B/D: D as is, B if drained 0%
C/D: D as is, C if drained 0%
Not rated 1%
Hydrologic soil group across mapped Dunstone acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Dunstone acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration0.0%
D: very slow infiltration (clayey, shallow or wet)98.7%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained0.0%
Not rated1.3%

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
All map unit components named Dunstone (component kind "Series") in SSURGO: 47,119 acres.
Method
Shares are by mapped acres of Dunstone components. The profile comes from the single largest Dunstone component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Dunstone.