Neb. Rev. Stat. § 23-309

The supervisors or board of county commissioners of any county in this state shall have the power, as hereinafter provided, to construct, establish or cause to be constructed and established any levee, dike, bank protection or current control in any river or stream wholly within or bordering on the respective counties, and to provide for the maintenance of the same, whenever such project shall be conducive to the public health, convenience, welfare or safety, which purpose shall or may include the protection of lands or property from overflow, wash or bank erosion.