Cal. Harbors and Navigation Code § 6090

All bonds issued pursuant to this part and Chapter 32, Statutes of 1901, page 27, are obligations of the district and so long as the bonds are outstanding and unpaid the board of supervisors of the county shall at the time of fixing the general tax levy and in the manner provided for such general tax levy until the bonds are paid or until there is a sum in the treasury of the district set apart for that purpose, sufficient to meet all sums coming due for principal and interest, levy and collect annually a tax sufficient to pay the annual interest on such bonds as it comes due and such part of the principal thereof as will become due before the proceeds of another tax levy made at the time of the next general tax levy for county purposes can be made available for the payment of said principal. In the event the district has moneys on hand in any year sufficient to meet all or part of the sum coming due for principal and interest on said bonds prior to the time that the proceeds of a tax levy made at the time of the next general tax levy for county purposes can be made available for the payment of said principal and interest and said moneys have been placed in a fund for the purpose of payment of said principal and interest the amount of moneys to be raised by the annual tax for that year may be reduced to a sum sufficient to provide the balance of moneys necessary for the purpose of payment of said principal and interest. All taxes collected for the payment of principal and interest, shall when collected by the county tax collector, be paid to the treasurer of said district.