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Which lock is first after Montreal Harbour on the St. Lawrence Seaway?

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Map showing the St. Lawrence hydrographic system and the five main sectors of the St. Lawrence Seaway project, stretching from Lake Ontario near Kingston through various locks, canals, and dams along the Canada-United States border to Montreal. The map highlights key locations such as the Thousand Islands, International Rapids, Lake St. Francis, Soulanges, and Lachine sections, with detailed labeling of major locks, canals, and power dams. Cross sections of the lock and canal system are depicted — St. Lawrence Seaway The St. Lawrence hydrographic system, with the five main sectors of the St. Lawrence Seaway project.

After Montreal Harbour, the first lock on the St. Lawrence Seaway is the St. Lambert Lock. This lock provides a lift of 4.6 metres (15 feet) to the Laprairie Basin.12