Garretson Soil Series
USDA Code: CA0216
K-Factor
0.32
Soil Erodibility Factor
Texture Class
loam
Drainage Class
well drained
About Garretson
Deep, well drained soils formed in alluvium from mixed crystalline and sedimentary rock sources. Found on alluvial fans and terraces.
K factor values are sourced from the USDA Natural Resources Conservation Service (NRCS) SSURGO database.
Using Garretson in a RUSLE calculation
For a California construction project, use the soil K factor with rainfall erosivity, slope length and steepness, cover management, and support practice inputs. The K factor represents the soil erodibility portion of the model, so selecting the soil series that matches the site is important for defensible stormwater documentation.
In a SWPPP workflow, the practical question is not just what soil type is mapped near the project. It is whether the mapped series, K factor, and drainage assumptions match the site evidence well enough to support the RUSLE or RUSLE2 calculation.
California Distribution
Found in Riverside and San Bernardino counties in inland Southern California. Common in the Inland Empire development corridors.
Counties Where Found
Garretson soil FAQ
What is the K factor for Garretson soil?
Garretson has a listed K factor of 0.32 in the Rapid RUSLE soil directory. Confirm final values against project specific soil survey data before submitting permit documents.
Where is Garretson soil found in California?
Garretson is mapped in Riverside, San Bernardino. County mapping is based on available soil series data and should be verified for the exact project location.
How is Garretson used in RUSLE erosion calculations?
Use the Garretson K factor as the soil erodibility input in RUSLE or RUSLE2, along with rainfall, slope, cover, and support practice factors for the site.
Calculate erosion risk with Garretson soil data
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