Gov. Code, § 28008

The board of supervisors may designate one or more state or national banks, one or more state or federal savings and loan associations, or one or more state or federal credit unions, doing business in the county as disbursing agent for the auditor to pay the salaries of such persons whose salaries are paid from the county treasury as may from time to time elect by a written instrument delivered to the auditor, to receive their salaries from such disbursing agent. In lieu of drawing separate salary warrants for such persons as shall have elected to be paid their salaries by such disbursing agent, the auditor may deliver to such disbursing agent a single warrant for the total combined salaries of such persons on or before the designated payday, together with the information necessary to disburse such salaries. The board of supervisors may enter into written contracts with such state and national banks, state or federal savings and loan associations, or state and federal credit unions, for their services as such disbursing agents on such terms as the board deems appropriate.