Neb. Rev. Stat. § 15-754

The city council of a city of the primary class shall have the power by ordinance to create public improvement districts for opening, widening, or enlarging of any street, alley, boulevard, or public way or the establishing or enlarging of any park or parkway within the city. Such special improvement district having been created, the city may acquire, by agreement, purchase, condemnation, or otherwise, the necessary lands, lots, or grounds to carry out the purposes of the district. The cost thereof may be, in whole or in part, assessed proportionate to benefits, on the property specially benefited. The city council shall have power and authority to fix the period of time for the payment of the special assessments and to issue bonds, as authorized by its home rule charter.