A district may to the extent authorized by the existing district be organized within, or partly within, the territorial boundaries of another district organized under this or other law, so long as the works or systems, their operation, the exercise of powers and the assumptions of duties and responsibilities, of one district, do not nullify, conflict with, or materially affect those of another preexisting district. A new district may not be organized within the boundaries of a preexisting district if the preexisting district disapproves within 30 days after mailing of notice pursuant to section 110A.13.