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.
- 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
Show as a table
| 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 |

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.
Where Auburn soil is found
Mapped acres
Auburn is mapped in California.
| 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
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 97.0% |
| Not rated | 3.0% |
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
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 97.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 3.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 28.7% |
| D: very slow infiltration (clayey, shallow or wet) | 68.3% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
| Not rated | 3.0% |
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.