Neb. Rev. Stat. § 70-636

The directors of any district organized under or subject to Chapter 70, article 6, are authorized to agree with the holders of any such revenue debentures, notes, warrants, bonds, or other evidences of indebtedness as to the maximum or minimum amounts which such district shall charge and collect for water, electric energy, radioactive material or the energy therefrom, hydrogen, ethanol, or other service sold by the district.