Neb. Rev. Stat. §§ 46-528
If an order is entered establishing the district, such order shall be deemed final. Any person, firm, or corporation owning real property within any reclamation district, created or established by virtue of the Reclamation Act, feeling himself or herself aggrieved by the establishment of such district, the determination of its boundaries, or the enclosure therein of any of his or her property may appeal the final order of the department adjudging such district to be duly incorporated. The appeal shall be in accordance with the Administrative Procedure Act, except that the appeal shall be to the district court of the county wherein the principal office of the reclamation district is located. If no appeal is taken within the time prescribed in the Administrative Procedure Act, the entry of such final order by the department shall finally and conclusively establish the regular organization of the district against all persons, except the State of Nebraska in an action in the nature of a writ of quo warranto commenced by the Attorney General within three months after the decree declaring such district organized as herein provided and not otherwise. The organization of such districts shall not be directly or collaterally questioned in any suit, action, or proceeding, except as herein expressly authorized.
Neb. Rev. Stat. §§ 46-528