Soil series profile

Auburn soil series

Auburn is a well drained soil with a silt loam surface, mapped on 260,338 acres in 13 counties in CA. Hydrologic group D.

#1335 by mapped area loamy Lithic Haploxerepts (Inceptisols)

Drainage class
Well drained
97% of mapped acres
Hydrologic group
D
68% of mapped acres
Typical topsoil pH
6.4
slightly acidic · range 6.1–6.7
Mapped area
260k
acres in 13 counties, 1 state

Typical Auburn profile

Texture and pH by depth

Typical Auburn soil profile by depth 0 in 10 in 0–14 in · H1 · pH 6.7 · 19% clay Silt loam 14–18 in · H2 Unweathered 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 Auburn horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–14 in (H1) Silt loam 6.7 19% 27% 1.5%
14–18 in (H2) Unweathered bedrock Not reported Not reported Not reported Not reported

Representative values from the most extensive Auburn map unit (Auburn very rocky silt loam, 2 to 30 percent slopes, survey area CA624). 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 Auburn soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Auburn soils is slightly acidic: pH 6.4 (most land between 6.1 and 6.7), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 97% of mapped Auburn acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (65% of mapped Auburn acres).

97% of mapped Auburn acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 97% 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 97% of the acres in mapped Auburn soils very limited, 0% somewhat limited and 0% not limited (3% 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 Auburn soil is found

Mapped acres

Auburn is mapped in California.

Counties with the most mapped Auburn soil
County Acres Share of county land
El Dorado County, CA 87,324 8.4%
Amador County, CA 45,972 12.6%
Placer County, CA 33,285 6.0%
Yuba County, CA 27,679 6.8%
Shasta County, CA 26,078 1.4%
Nevada County, CA 23,028 1.7%
Stanislaus County, CA 3,708 0.4%
Calaveras County, CA 3,500 0.3%
Tuolumne County, CA 3,500 0.2%
Butte County, CA 2,159 0.2%
Merced County, CA 1,750 0.1%
Mariposa County, CA 1,089 0.1%
Sacramento County, CA 669 0.1%

Septic absorption fields

NRCS rating, share of Auburn acres

Not limited 0%
Somewhat limited 0%
Very limited 97%
Not rated 3%
Septic tank absorption field rating across mapped Auburn acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Auburn acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited97.0%
Not rated3.0%

Drainage, water table and flooding

Share of Auburn 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 9–40% (median 16%).
Topsoil organic matter
Median 1.5%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 97%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 0%
Very poorly drained 0%
Not rated 3%
Drainage class across mapped Auburn acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Auburn acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained97.0%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained0.0%
Very poorly drained0.0%
Not rated3.0%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 0%
C: slow infiltration 29%
D: very slow infiltration (clayey, shallow or wet) 68%
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 3%
Hydrologic soil group across mapped Auburn acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Auburn acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration28.7%
D: very slow infiltration (clayey, shallow or wet)68.3%
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 rated3.0%

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 Auburn (component kind "Series") in SSURGO: 260,338 acres.
Method
Shares are by mapped acres of Auburn components. The profile comes from the single largest Auburn component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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