Idaho Code § 42-3217
Whenever any indebtedness has been incurred by a district, it shall be lawful for the board to levy taxes and collect revenue for the purpose of creating a sinking fund in such amount sufficient to meet the payments of principal and interest on such indebtedness as the same matures, and to constitute a sinking fund for the payment of the principal amount of the indebtedness within thirty (30) years from the time of contracting the indebtedness evidenced thereby and in accordance with the provisions made for the payment of the principal and interest of such indebtedness and also to constitute a sinking fund for payment of the principal thereof, and theretofore provided by resolution pursuant to section 42-3222, Idaho Code, and as required by the constitution and laws of the state of Idaho.
Idaho Code § 42-3217