Neb. Rev. Stat. §§ 31-1020
If a local government does not adopt and implement flood plain management regulations in accordance with section 31-1019 within one year after flood hazard data and maps have been provided to it pursuant to such section, the department shall, upon petition of at least ten percent of the owners of the land located within the flood plain of the base flood delineated in such maps, or upon the written request of the board of directors of the natural resources district in which such land is located, conduct a public hearing after providing notice pursuant to section 31-1022. If the department finds after such hearing that the data and maps available are sufficient to reasonably locate the boundaries of the base flood, the department shall determine and fix by order the boundaries of the base flood and, where deemed appropriate, the boundaries of the floodway within the zoning jurisdiction of such local government. If within three months after the date of such order the local government still has not adopted and implemented flood plain management regulations for the area subject to such order in accordance with section 31-1019, the department shall be vested with the power and authority to adopt flood plain management regulations for the area and shall adopt and promulgate such regulations for the identified base flood within the zoning jurisdiction of such local government. Such regulations shall be consistent with the minimum standards adopted by the department pursuant to subdivision (5) of section 31-1017 and shall take effect on the date prescribed by the department. All ordinances or other actions by the local government which are contrary to the rules and regulations of the department shall be null and void.
Neb. Rev. Stat. §§ 31-1020