The boards and general managers shall operate the Proprietary Departments for the following purposes, which shall be known as the Departmental Purposes:
Airports: In connection with, or for the promotion and accommodation of air commerce and air navigation.
Harbor: In connection with, or for the promotion and accommodation of maritime commerce, navigation, and fishery.
Water and Power: In connection with, or for the production and delivery of water and electric power, and for the promotion of the conservation of water and power resources.