The formation petition shall be signed by voters equal in number to at least 10 per centum of the voters registered within the boundaries of the proposed district 30 days prior to the date the petition is filed. If one or more cities are included in the proposed district, the formation petition shall, in addition, be signed by at least 10 percent of the voters of each such city registered to vote 30 days prior to the date the petition is filed.
Ca. Water Code § 71121