Cal. Educ. Code § 17022

Except as provided in Section 17041, the board shall not approve any new school facilities for any applicant school district or county superintendent of schools until it first has made a determination that the applicant will utilize all existing facilities and sites to the extent economically and practically feasible. The board may also require the applicant to explore cooperative efforts with adjacent districts or, in the case of county superintendents of schools, with adjacent county superintendents of schools, in order that all existing or planned facilities in the general area of need shall be utilized.