From the Organization Document:

To supplement the Sheriff's capabilities in routine operations (e.g. neighborhood patrols) and provide a pool of trained, pre-qualified, well-coordinated teams during non-routine operations (e.g. a disaster). The Auxiliary is not intended to replace deputies or the Reserve Deputy Program, in or out of an emergency, but to provide complementary skills and provide opportunities for community members to participate who do not desire a career in law enforcement. The Auxiliary is intended neither to provide primary law enforcement nor criminal investigative skills. The Auxiliary answers to the Office of the Sheriff when properly called up and directed in an emergency; Auxiliary members have no authority when not empowered and directed by the Sheriff. At the same time, the Auxiliary shall not be the personal gang of the Sheriff and is to be used only in the furtherance of public order and in defense of the community at large.

The Organization Document goes into further detail on anticipated mission and tasks.