Water Code §51.433

(a) At the time bonds are voted, the board shall levy a tax on all property inside the district in a sufficient amount to redeem and discharge the bonds at maturity. (b) The board annually shall levy or have assessed and collected taxes on all property inside the district in a sufficient amount to pay for the expenses of assessing and collecting the taxes. (c) If a contract is made with the United States, the board annually shall levy taxes on property inside the district in a sufficient amount to pay installments and interest as they become due. (d) The board may issue the bonds in serial form or payable in installments, and the tax levy shall be sufficient if it provides an amount sufficient to pay the interest on the bonds, the proportionate amount of the principal of the next maturing bonds, and the expenses of assessing and collecting the taxes for that year.