Neb. Rev. Stat. §§ 46-142
Upon the presentation of the coupons and bonds due at the office of the treasurer of the county in which the district was originally organized, it shall be his or her duty to pay the same from the bond funds. Whenever, after ten years from the issuance of the bonds, the sinking fund shall amount to the sum of ten thousand dollars, the board of directors may direct the county treasurer in which the district was originally organized to pay such an amount of the bonds not due as the money of the fund will redeem, at the lowest value at which they may be offered for liquidation, after advertising for at least three weeks in some daily newspaper in each of the cities hereinbefore named, and in any newspaper which the board may deem advisable, for sealed proposals for the redemption of the bonds. Such proposals shall be opened by the board in open meeting, at the time named in the notice, and the lowest bid for the bonds must be accepted. No bond shall be redeemed at a rate above par. In case the bids are equal, the lowest numbered bond shall have the preference. In case none of the holders of the bonds shall desire to have the same redeemed, as herein provided, the money shall be invested by the treasurer of the county in which the district was originally organized, under the direction of the board of directors of the district, in United States bonds, or the bonds or warrants of the state, which shall be kept in the bond fund, and may be used to redeem the district bonds whenever the holders thereof may desire.
Neb. Rev. Stat. §§ 46-142