Cal. Education Code § 35100

Within 15 days after the action necessary for the formation of any elementary school district or high school district is completed, the county superintendent of schools shall appoint an interim governing board. Within 15 days after the action necessary for the formation of any joint or joint union elementary school or high school district is completed, the county superintendent of schools having jurisdiction over the district shall appoint a majority of the members of an interim governing board. If the new district is in two counties, the other county superintendent shall appoint the rest of the interim governing board members within such 15-day period. If the new district is in more than two counties, the other county superintendents shall appoint the rest of the interim governing board members within such 15-day period as may be agreed upon by them. If they cannot agree within such 15-day period, the county superintendent who appointed the majority of the interim governing board members shall appoint the rest of the members. The term of each governing board member so appointed shall expire on the April 1st following the election of the first elected governing board of the district. If a majority of the members of the interim governing board of the school district is not appointed and qualified within such 15-day period, the county superintendent of schools having the power to appoint the interim governing board, or a majority thereof, shall assume the powers and duties belonging to the governing board until a majority of the governing board is selected and qualified.