The St. Lawrence / Great Lakes System
The St. Lawrence is part of a complex system, which includes the Great Lakes, the St. Lawrence Seaway and a dredged channel between Quebec and Montreal. The main purpose of the Seaway is to provide a maritime link between Montreal, an ocean port, and the Great Lakes by using a series of locks and canals. The best known is the Welland Canal linking Lake Ontario and Lake Erie, a 99 meters climb over the Niagara escarpment. The major issue of the seaway is related to its limited capacity and being close for a few months during the winter.
The St. Lawrence itself can be subdivided between the estuary which is accessible to deep navigation and the river where vessels close to the Panamax standard can access year round the Port of Montreal. Its channel is 11.3 meters (37 feet) can handle containerships up to 4,100 TEU.
| Length | 3,060 km |
| St. Lawrence sub-basin | 574,000 sq. km |
| Great Lakes sub-basin | 770,200 sq. km |
| Total basin | 1,344,200 sq. km |
| Mean flow | 10 cubic m./s |
| Population | approx. 5 millions over a 10 km-wide strip along the St. Lawrence. If we consider the St. Lawrence / Great Lakes region, it accounts for a total of 90 million people. |
| Economic facts | 40% of American manufacturing (70% of steel production) and 66% of Canada's industrial production in the region. |