The board of trustees of a regional water and sewer district may enter into contracts or other arrangements with the United States government or any department thereof, with persons, firms, or corporations, with public corporations and the state government of this state or other states, with drainage, conservation, conservancy, sewer, park, or other improvement districts in this or other states for co-operation or assistance in planning, constructing, maintaining, using, and operating the works of the district, or in minimizing or preventing damage to its properties, works, and improvements, or for making surveys, investigations, or reports thereon.