Question about using STATSGO2 soil map with QSWAT+ built-in STATSGO db/lookup table

[Fereshteh Kordrostami]

Hello all,

I downloaded the STATSGO2 spatial and tabular data from USDA/NRCS Web Soil Survey for California. The spatial layer contains fields such as MUKEY and MUSYM. I followed the instructions in "Using SSURGO and STATSGO2 soil data with QSWAT; Chris George, 2015" to create an integer field from MUKEY and to rasterize the polygon layer using this integer MUKEY field as the raster value.

The raster itself seems to be valid. For example, one of the raster cell values is:
660626

However, when I use this STATSGO2 raster in QSWAT+ with the built-in STATSGO lookup table/soil database, QSWAT+ cannot recognize the soil IDs. I checked the SWAT+ SQLite soil database for STATSGO, and the value 660626 does not exist there.

The SWAT+ STATSGO soil database appears to use identifiers such as:
muid = AL001
s5id = TN0042
name = DICKSON

But the NRCS STATSGO2 data I downloaded uses identifiers such as:
MUKEY = 660626
MUSYM = s523

So my question is:

Where can I obtain the STATSGO soil map that matches the built-in SWAT+ STATSGO lookup table and soil database?

Or, alternatively:

Is there an official crosswalk or foreign key that connects NRCS STATSGO2 MUKEY / MUSYM values to the SWAT+ STATSGO database fields?

If no such map or crosswalk exists, is the recommended approach to build a custom SWAT+ soil database/soils.sol file from the NRCS STATSGO2 tabular files by selecting a representative component for each MUKEY?

Any guidance on the correct workflow for using STATSGO2 with QSWAT+ would be greatly appreciated.

Best regards,
Fereshteh