Neb. Rev. Stat. § 10-715: Neb. Rev. Stat. § 10-715

The tax and funds so collected shall be deemed pledged and appropriated to the payment of the interest and principal of the registered bonds herein provided for, until fully satisfied, and the treasurer shall be liable on his official bond for the faithful disbursement of all money so collected or received by him. After the principal and interest of such bonds shall have been fully paid, and all obligations for which such fund and taxes were raised have been discharged, the county clerk, upon the order of the county board, shall notify the county treasurer to transfer all such funds remaining in his hands to the credit of the district to which they belong.