The Saint Lawrence Seaway in its broadest sense (see Great Lakes Waterway) is the system of canals that permits ocean-going vessels to travel from the Atlantic Ocean to the Great Lakes as far as Lake Superior. However, according to law, the Saint Lawrence Seaway extends from Montreal to Lake Erie and includes the Welland Canal.
The seaway begins at the port of Montreal, where the South Shore Canal (St-Lambert and Côte Ste-Catherine canal locks) passes the Lachine Rapids. West of the Island of Montreal and Lac Saint-Louis, the Beauharnois canal and locks pass the Beauharnois hydroelectric dam. The seaway then leaves Quebec through Lac Saint-François and the Akwesasne Mohawk First Nation, and passes through New York State and Ontario. In New York, the Wiley-Dondero Canal (Snell and Eisenhower locks) passes the Moses-Saunders power dam, and the short Iroquois lock passes the Iroquois water level control structure. Altogether there are seven locks in the Montreal-Lake Ontario section (5 Canadian, 2 American).
The Welland Canal (eight locks) links Lake Ontario to Lake Erie, bypassing the formidable barrier of Niagara Falls.
The seaway is co-administered by Canada and the United States. It was first used on April 25, 1959, although it wasn't officially opened until June 26th, 1959 by Queen Elizabeth II and President Dwight Eisenhower.
To create a navigable channel through the Long Sault rapids and allow hydroelectric stations to be established at Cornwall, Ontario and Massena, New York, a man-made lake, Lake Saint Lawrence, was created. This required the inundation on July 1, 1958 of ten villages in Ontario, now collectively known as "The Lost Villages."
The creation of the Seaway also led to the introduction of foreign species of aquatic animals, including the sea lamprey and the zebra mussel, into the Great Lakes watershed.
- Great Lakes St. Lawrence Seaway System web site (http://www.greatlakes-seaway.com/en/home.html)
- The Lost Villages Historical Society (http://lostvillages.ca)