The county board may, after public hearing on the petition, thereupon change the boundaries of the original drainage district organized under the provisions of Chapter 31, article 3 or 4, so as to include the area benefited by the drainage ditch constructed under the provisions of sections 31-101 to 31-134, or by the drainage district which has been dissolved; Provided, that the county board shall first find and determine that such change of boundaries is just and will be conducive to the public health, convenience or welfare.
Neb. Rev. Stat. §§ 31-141