County soil summary
Soil types in San Bernardino County, California
The most widespread soils are Cajon, Arizo and Dalvord; the most common drainage class is well drained (37% of the land), and typical topsoil pH is 7.9.
About 275,000 acres of San Bernardino County lie in multi-county soil survey areas (CA682, CA695, CA698, CA776, CA794, CA803, CA805) that the soil survey does not split by county. Those acres, often public forest or desert land, are counted in the California totals but not in the figures below.
- Well or moderately well drained
- 86% of land · state 81%
- Typical topsoil pH
- 7.9 moderately alkaline · state 6.7
- Septic fields very limited
- 71% of land · state 79%
- Subject to flooding
- 20% of land, any frequency · state 11%
Most common soils in San Bernardino County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 30% of the mapped land; 335 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Cajon | 7.3% | Somewhat excessively drained | 7.9 |
| Arizo | 6.7% | Excessively drained | 8.0 |
| Rock outcropLand type, not a soil series | 5.2% | — | — |
| Dalvord | 3.4% | Somewhat excessively drained | 8.0 |
| Carrizo | 2.6% | Excessively drained | 7.9 |
| Dalelake | 1.7% | Somewhat excessively drained | 7.6 |
| Bryman | 1.6% | Well drained | 7.9 |
| Helendale | 1.6% | Well drained | 7.9 |
What this means
What the soils in San Bernardino County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in San Bernardino County is moderately alkaline: pH 7.9 (most land between 6.7 and 8.2). Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).
Sandy topsoil covers 45% of the land. It drains fast and warms early in spring, but dries out and loses nutrients quickly: mulch, compost and steady watering help. The most common surface texture is sandy loam (8% of the land).
46% of the land is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.
For your lawn and yard
42% of the land is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.
For a septic system
For conventional septic absorption fields, NRCS rates 71% of the land in San Bernardino County very limited, 6% somewhat limited and 11% not limited (12% not rated, such as urban land, pits or water).
Statewide, 79% of the land is very limited, so San Bernardino County 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 20% of the land (2% occasional, 2% 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 (37%). 86% of the land is moderately well drained or better, compared with 81% across California.
Show as a table
| Category | San Bernardino County | California |
|---|---|---|
| Excessively drained | 13.9% | 7.7% |
| Somewhat excessively drained | 32.5% | 17.6% |
| Well drained | 36.6% | 50.7% |
| Moderately well drained | 2.5% | 4.7% |
| Somewhat poorly drained | 0.6% | 2.5% |
| Poorly drained | 0.1% | 2.0% |
| Very poorly drained | 0.0% | 0.7% |
| Not rated | 13.8% | 14.2% |
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 | San Bernardino County | California |
|---|---|---|
| Not limited | 10.6% | 4.3% |
| Somewhat limited | 6.0% | 3.6% |
| Very limited | 71.3% | 79.2% |
| Not rated | 12.0% | 12.9% |
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 | San Bernardino County | California |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 41.7% | 20.5% |
| B: moderate infiltration | 8.5% | 12.5% |
| C: slow infiltration | 12.4% | 22.7% |
| D: very slow infiltration (clayey, shallow or wet) | 26.0% | 30.3% |
| A/D: D as is, A if drained | 0.0% | 0.3% |
| B/D: D as is, B if drained | 0.0% | 0.3% |
| C/D: D as is, C if drained | 0.0% | 0.9% |
| Not rated | 11.4% | 12.6% |
Flooding
Show as a table
| Category | San Bernardino County | California |
|---|---|---|
| No flooding | 65.7% | 77.1% |
| Rare or very rare | 16.2% | 8.2% |
| Occasional | 1.7% | 1.6% |
| Frequent or very frequent | 1.8% | 1.0% |
| Not reported | 14.6% | 12.1% |
Seasonal high water table
Show as a table
| Category | San Bernardino County | California |
|---|---|---|
| Within 18 inches at some time of year | 0.4% | 2.6% |
| 18 inches to 3.3 feet | 0.1% | 1.9% |
| Deeper than 3.3 feet or none reported | 90.4% | 86.9% |
| Not reported | 9.1% | 8.6% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 7.9 (moderately alkaline); 80% of rated land falls between 6.7 and 8.2. Median topsoil organic matter is 0.2%.
Show as a table
| Category | San Bernardino County | California |
|---|---|---|
| Strongly acidic (below 5.5) | 0.0% | 3.1% |
| Moderately to slightly acidic (5.5–6.4) | 1.8% | 22.8% |
| Near neutral (6.5–7.3) | 15.5% | 25.2% |
| Alkaline (7.4 and up) | 66.6% | 30.6% |
| Not reported | 16.0% | 18.2% |
Texture
Show as a table
| Category | San Bernardino County | California |
|---|---|---|
| Sandy | 44.5% | 21.3% |
| Loamy (loam, silt loam and similar) | 39.2% | 56.7% |
| Clayey (40%+ clay) | 0.3% | 3.9% |
| Organic (muck or peat) | 0.0% | 0.2% |
| Not reported (rock, urban land, etc.) | 16.0% | 18.0% |
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
- San Bernardino County, California (FIPS 06071): 5,403,669 acres of mapped land, 22,498 acres of open water excluded. State comparisons pool all mapped land in California.
- 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.