La. Stat. tit. 33 § 3828
The governing authority of any such political subdivision complying with the provisions of R.S. 33:3822 through 33:3835 shall have the power and is hereby authorized to issue, execute, negotiate, sell and deliver, negotiable interest bearing coupon certificates of the political subdivision in an amount not exceeding the total amount of the installments or deferred payments as provided for in R.S. 33:3827, and certificates to bear interest not exceeding 6% per annum, said interest to be paid annually and said certificates to mature serially over a period not exceeding forty years, but in no event shall said certificates extend over a longer period of time than that provided for by the ordinance levying the local or special assessments which may be payable in annual installments. Said certificates shall be of such form, date, denomination, and payable in principal and interest at such time and place as the governing authority may determine, the payment of such certificates to be secured in principal and interest by the irrevocable pledge and dedication of the funds derived from the levying and collection of the special assessments as hereinabove provided for by R.S. 33:3822 through 33:3835, and which funds shall be set aside in a separate fund and shall not be drawn upon for any other purpose than to pay the principal and interest of said certificates, provided, however, that the governing authority may issue amortized promissory notes without coupons providing for partial payments of principal and accrued interest at stated periods for a definite time at the expiration of which the entire debt will be extinguished, which notes shall not be for a longer period than forty (40) years and shall bear interest not to exceed 6% per annum and which notes may be secured by property belonging to said political subdivision whether said property be movable or immovable, and/or by a pledge of anticipated revenues from the sale of water by said district.
La. R.S. § 33:3828