A port district may construct, condemn, purchase, acquire, add to, maintain, conduct, and operate sea walls, jetties, piers, wharves, docks, boat landings, and other harbor improvements, warehouses, storehouses, elevators, grain-bins, cold storage plants, terminal icing plants, bunkers, oil tanks, ferries, canals, locks, tidal basins, bridges, subways, tramways, cableways, conveyors, administration buildings, fishing terminals, together with modern appliances and buildings for the economical handling, packaging, storing, and transporting of freight and handling of passenger traffic, rail and motor vehicle transfer and terminal facilities, water transfer and terminal facilities, air transfer and terminal facilities, and any combination of such transfer and terminal facilities, commercial transportation, transfer, handling, storage and terminal facilities, and improvements relating to industrial and manufacturing activities within the district, and in connection with the operation of the facilities and improvements of the district, it may perform all customary services including the handling, weighing, measuring and reconditioning of all commodities received. A port district may also construct, condemn, purchase, acquire, add to and maintain facilities for the freezing or processing of goods, agricultural products, meats or perishable commodities. A port district may also construct, purchase and operate belt line railways, but shall not acquire the same by condemnation.