Cal. Education Code § 45300

Eligibility lists shall be established for a period of not less than one year except that when a list is exhausted for appointments to current vacancies, through use and eligibles being unavailable, the commission may, upon the recommendation of the officer charged with certifying eligibles, and after due notice to eligibles who may have made themselves unavailable for appointment, terminate it before a year has expired. Eligibility lists may be established for a period of six months upon the approval of the personnel commission as long as the six-months’ duration of such a list is noted in the recruitment bulletin announcing the examination. If a list is exhausted for appointments to current vacancies, through use and eligibles being unavailable, the commission may, upon the recommendation of the officer charged with certifying eligibles, and after due notice to eligibles who may have made themselves unavailable for appointment, terminate it before the expiration date. A list may be extended for an additional period of two years or less at the discretion of the commission.