Neb. Rev. Stat. § 46-1,101

Such bonds, and the interest thereon, shall be paid by revenue derived from an annual assessment upon the real property of the district and all the real property of the district shall be and remain liable to be assessed for such payments as herein provided, and for all payments due or to become due to the United States under any contract between the district and the United States, accompanying which bonds of the district have not been deposited with the United States as provided in section 46-126 .