California Code, Business and Professions Code - BPC § 23770

A winegrower's license, or a wine blender's license, whichever is appropriate to the operations to be conducted on the licensed premises, shall be issued only to, or held by, a person qualified to operate or operating a winery or wine cellar bonded under the internal revenue laws of the United States.  Every person operating, or authorized under the internal revenue laws of the United States to operate, a winery or wine cellar bonded under the internal revenue laws of the United States shall apply for, and hold, a winegrower's or wine blender's license, as may be appropriate for operations conducted on the licensed premises.