California Code, Government Code - GOV § 31000.4

The board of supervisors may contract with temporary help firms for temporary help to assist county agencies, departments, or offices during any peak load, temporary absence, or emergency other than a labor dispute, provided the board determines that it is in the economic interest of the county to provide such temporary help by contract, rather than employing persons for such purpose.  Use of temporary help under this section shall be limited to a period of not to exceed 90 days for any single peak load, temporary absence, or emergency situation.