Neb. Rev. Stat. § 37-551: Neb. Rev. Stat. § 37-551

For the purpose of protecting the game fish in the streams or rivers and reservoirs of this state whose waters are used for purposes of irrigation, the commission may provide and cause to be placed and maintained, at the mouth of every irrigation ditch designated by it and which opens into such stream or river or reservoir containing trout, bass, crappie, and pickerel in this state, a workable woven wire fish screen having a mesh no larger than one inch.