Cal. Pub. Util. Code § 13212

If the proposition submitted at a special bond election fails to receive the requisite number of votes, the board shall not within six months after the election hold another special election for the submission of a proposition of incurring a bonded indebtedness substantially the same as the proposition voted upon at the prior election unless a petition signed by voters within the district equal in number to at least 15 percent of the total vote cast is filed with the board, requesting that the proposition, or a proposition substantially the same, be submitted at an election to be called for that purpose.