If bonds have been voted and sold by the district, the board shall include in the annual estimate an amount which, together with any moneys available therefor in the bond fund, shall be at least sufficient to pay all bond principal and interest coming due during the ensuing fiscal year and also during that part of the following fiscal year before the proceeds of an assessment tax levied at the time for making the general tax levy in such following fiscal year can be made available for the payment thereof, and such estimate each year shall include an amount clearly sufficient to provide for the payment of principal of and interest on bonds of the district as the same become due.
Ca. Water Code § 75353