St Lawrence Seaway (Great Lakes Waterway) is the system of locks, canals and channels linking the Great Lakes and the St Lawrence River with the Atlantic Ocean. The construction of progressively larger canals along the St Lawrence River began as early as 1783. By 1900, a complete network of shallow draft canals allowed uninterrupted navigation from Lake Superior to Montréal.
Between 1912 and 1932, the WELLAND CANAL was rebuilt, but the US was reluctant to enter a larger scheme, that is, to rebuild the Montréal-Lake Ontario channels. A threat by the Canadian government in 1951 to build a seaway entirely within Canadian territory resulted in a final agreement in 1954. Construction began that year on the Montréal-Lake Ontario section. This was opened to commercial traffic 20 Apr 1959 with the official opening 26 June 1959, attended by PM John Diefenbaker, Pres Dwight D. Eisenhower and Queen Elizabeth II.
The waterway, some 3790 km long from Anticosti Island to the head of Lake Superior, now permitted vessels of up to 222.5 m long, 23.2 m wide and a maximum draft of 7.9 m to sail from Montréal to Duluth, Minn, on Lake Superior.
The St Lawrence Seaway Authority, a federal crown corporation, was established by Act of Parliament in 1954 to construct, operate and maintain the Canadian portion of the waterway between Montréal and Lake Erie, including 5 of the 7 locks between Montréal and Lake Ontario and the Welland Canal between Lake Ontario and Lake Erie.
The St Lawrence Seaway Development Corp was similarly formed by the US government to operate the 2 locks near Massena, NY. The 4 US locks on the St Mary's River are operated by the US Corps of Engineers and a smaller lock (18.3 m), too small for most commercial vessels, on the Canadian side of the St Mary's River is operated by Environment Canada, Parks.
Construction of the Seaway was a monumental engineering and construction feat. The Montréal-Lk Ontario section, which is often thought of as the whole Seaway, naturally divides into 4 sectors. The Lachine section includes the 33 km South Shore Canal, with the St Lambert and Côte Ste Catherine locks bypassing the Lachine Rapids. The 2 locks provide a total lift of 13.7 m to the level of Lake St Louis. The Soulanges section includes the 2 Beauharnois locks which provide a total lift of 25 m to overcome the Beauharnois hydroelectric power dam. A further channel of 25.6 km leads westward to Lake St Francis. The Lake St Francis section stretches from the Beauharnois Canal to a point just east of Cornwall, Ont.
The fourth section, the Wily-Dondero Ship Canal, which includes the US-owned Snell and Eisenhower locks near Massena, NY, allows ships to bypass the Moses/Saunders powerhouse. These 2 locks provide a lift of some 26 m to the level of Lake St Lawrence. At the W end of this lake the Iroquois lock, located at Iroquois, Ont, and adjacent to the Iroquois control dam, provides for control of the level of Lake St Lawrence relative to that of Lake Ontario. Together, all these locks between Lake Ontario and Montréal lift a westbound vessel about 65 m. West of Iroquois additional dredging was required to complete the St Lawrence Seaway to Lake Ontario.
In addition to the primary works required to create the Seaway, ancillary works such as major bridge and tunnel construction were carried out in Montréal, Beauharnois, Cornwall and Massena. In addition, the creation of Lake St Lawrence necessitated the relocation of highways and railways, as well as several small communities and parts of the towns of Iroquois and Morrisburg. In all over 500 dwellings and 6500 people were relocated to the newly created towns of Ingleside and Long Sault.
Between Lake Ontario and Lake Erie, the Welland Canal circumvents Niagara Falls. Its 8 locks lift a westbound vessel 99.4 m over a distance of 42.5 km. Between Lake Erie and Lake Huron, the US deepened the Detroit River, the St Clair River and Lake St Clair. The St Mary's River Canal links Lake Huron and Lake Superior. Each of its 4 parallel locks, on the US side, lifts a westbound vessel the required 6.5 m to bypass the St Mary's Falls.
The expenditure of public funds on the Seaway was not without opposition. The construction of the Seaway was considered by the railways and E coast ports to be unfair subsidized competition. Shippers, although in favour of the Seaway, opposed implementation of tolls. The original St Lawrence section of the Seaway cost Canada $330 million and the US $130 million. Canada has paid a further $300 million to improve the Welland Canal.
Repayment of capital debt, interest and operating costs could not be covered under existing financial arrangements, and in 1977 a change in legislation converted the Canadian Seaway Authority debt to equity held by Canada but required that revenues cover all operating and maintenance costs; this change has been successful. An additional $600 million spent by the 2 countries for hydroelectric development has been recovered by electricity sales.
The Seaway has a major economic impact on Canada and the US. It provides economical freight rates for bulk commodities and makes an important contribution to the basic industries of both countries. The Seaway made possible the exploitation of the vast IRON ORE deposits of Québec and Labrador, and turned Canada from an importer to an exporter of iron ore.
In 1986, 37.6 million t of cargo moved through the St Lawrence section of the Seaway, in contrast with the annual average of about 11 million t moved in the 1950s. Of the volume of cargo moving through the Seaway in 1986, 44% was grain, about 21% was iron ore, 22% was other bulk cargo and another 11% was general cargo or finished goods (most imported iron and steel products).
Coal moving to Ontario steel mills and ELECTRIC-POWER GENERATING stations was important cargo on the Welland Canal.
