Cal. Pub. Util. Code § 18054

The board shall annually, at the time of levying taxes for general district purposes, fix a rate of ad valorem tax upon the taxable real property in the zone created therefor, sufficient to pay the zone bond principal and interest as they become due before the proceeds of another such levy shall be available therefor, and such tax shall be levied, collected and money collected therefrom shall be expended to pay zone bonds principal and interest, in the same manner and with the same effect as taxes levied to pay bonds of the district pursuant to Article 8 (commencing with Section 16641), Chapter 4 of this division.