Iowa Code § 28J.15

A political subdivision creating or participating in the creation of a port authority in accordance with section 28J.2 shall not, during the time the port authority is in existence, exercise the rights and powers provided in chapters 28A, 28K, and 384 relating to the political subdivision’s authority over a port, wharf, dock, harbor or other facility substantially similar to that political subdivision’s authority under a port authority granted under this chapter.