La. Stat. tit. 38 § 1654
A sufficient amount of the drainage tax shall be appropriated by the board of commissioners for the purpose of paying the principal and interest of the bonds, and the taxes, when collected, shall be preserved in a separate fund for that purpose and no other. All bonds and coupons not paid at maturity shall bear interest at the rate of six per centum per annum from maturity until paid, or until sufficient funds have been deposited at the place of payment, named in the bonds and coupons, and the interest for deferred payment shall be appropriated by the board of commissioners out of the penalties and interest collected on delinquent taxes or any other available funds of the district. Any expense incurred in paying the bonds and interest thereon and a reasonable compensation to the bank or trust company for paying the same, shall be paid out of other funds in the hands of the district and collected for the purpose of meeting the expense of administration. The board of commissioners in making the annual tax levy, as heretofore provided, shall take into account the maturing bonds and interest on all bonds and to make an ample provision in advance for the payment thereof.
La. R.S. § 38:1654