Neb. Rev. Stat. § 31-429

Lands within the drainage district which have been assessed for benefits may, under general rules and regulations to be made by the board of directors applicable to all similarly situated, be drained by the owners thereof by tiling or otherwise into the main or lateral drains. Owners of land within the district not assessed, or without the district, may drain such lands into the main or lateral drains of the drainage district upon contracting with the board of directors for the privilege, and paying therefor, but not otherwise.