The Canada Marine Act, passed in 1998 under the stewardship of David Collenette, Minister of Transport, was an act intended to modernize Canada's most important ports, and make "the system of Canadian ports competitive, efficient and commercially oriented, providing for the establishing of port authorities and the divesting of certain harbours and ports, for the commercialization of the St. Lawrence Seaway and ferry services and other matters related to maritime trade and transport and amending the Pilotage Act and amending and repealing other Acts as a consequence."
The Act designated 19 ports as economically significant. Each of those ports was to have a port authority created for it. The act had provision to allow additional ports to have port authorities created to oversee their operation. An exception was made for the port facilities at Churchill, Manitoba, North America's only port on the Arctic Ocean connected to the North American Railroad Grid. The act downloaded the mandate to oversee the operation of 150 smaller ports to the provinces or municipalities in which they were contained. Thirty-four remote ports remain under direct supervision by the Department of Transport.
The Port of Sydney, NS is not part of this system.
Oddly, the Welland Canal, which is part of the Saint Lawrence Seaway, seems to be regulated under the Fishing and Recreational Harbours Act (R.S., 1985, c. F-24) which falls to the Department of Fisheries and Oceans. Port Dalhousie is subject to the Fishing and Recreational Harbours Regulations, while Port Colborne seems to fall under the Ontario Fishery Regulations.
Responsibility for the construction and operation of canals had been given to the Department of Public Works at the time of Confederation, with the canals of the United Province of Canada having been previously operated by that colony's Department of Public Works. Things were simpler then. Since 1995, the Minister of Public Works and Government Services Canada has taken care of these affairs. A vestigial reminder of the past is that the Ottawa River, which once was an important part of the economy with for example the Ottawa River timber trade, and "all canals or other cuttings for facilitating such navigation, and all dams, slides, piers, booms, embankments and other works of what kind or nature soever in the channel or waters" is wholly governed under this Ministry's An Act respecting certain works on the Ottawa River. Most of the other heritage waterways of Ontario and a few in Quebec are governed by Parks Canada under the guidance of the Minister of the Environment.