Whenever a sanitary drainage district shall have been formed under sections 31-501 to 31-523, and trustees thereof have been elected, if such trustees find that a municipality formerly within the boundaries of such sanitary district has grown and enlarged its corporate limits beyond the boundaries of such sanitary district, the board of trustees may by resolution include the whole of the corporate area of such municipality within its boundaries by enlarging same.
Neb. Rev. Stat. §§ 31-549