The St. Lawrence River: Gateway to North America

ST. LAWRENCE INFO

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The St. Lawrence River: Gateway to North America

Canada is bounded by three oceans — the Pacific, the Atlantic and the Arctic — and traversed by the largest inland waterway accessible to ocean-going vessels in the world. Recognized today as one of the main gateways to the North American continent, the St. Lawrence waterway, which stretches a distance of 3700 km from Cornwall, Ontario, to the Gulf of St. Lawrence, was shaped over time.

	In colonial times, ocean-going boats sailed upstream to Quebec City. From there, a river fleet (wooden canoes, sailboats, longboats, barges, etc.) provided transport to Montreal. The journey between Montreal and the Great Lakes was made by birch bark canoe. As early as 1700, the first initiative was taken to improve transport on the St. Lawrence River. The project consisted of creating a channel 1.6 km long, 3.6 m wide and 0.45 m deep to bypass the Lachine Rapids. It was never completed. In 1783, the British Army constructed four bypass canals with locks between lakes Saint-François and Saint-Louis. In 1825, the Lachine Canal, 13.6 km in length and 1.5 m deep, with six locks, was completed. In 1959, a deepwater channel (minimum depth: 8.2 m) was constructed between Lake Ontario and Montreal.
Lachine Canal

Building canals on the St. Lawrence Seaway in 1958

St. Lawrence waterway between Cornwall and the Gulf
From the Gulf to Pointe d’Alliance (near Cap Tourmente)	Natural deepwater waterways
From Pointe d’Alliance to Montreal	Ship channel consisting of a dug channel linking natural basins
From Montreal to Cornwall	Seaway composed of canals, dredged channels and seven locks
Saguenay Fjord	Waterway consists of a natural channel from the river mouth to La Baie
Source: St. Lawrence Centre and Laval University, 1991, cited in Villeneuve and Quilliam, 2000.

Changes in St. Lawrence River ship channel clearances

Large-scale Projects on the Riverbed of the St. Lawrence

Construction of the St. Lawrence Seaway and its seven locks would transform the river into a massive worksite during the 1950s. A huge amount of material, close to 63 million cubic metres of sediment, was excavated from the riverbed in the Quebec and Ontario portions of the river. In 1952, the minimum water depth in the ship channel was thus increased to 10.7 metres downstream of Montreal.

A later phase of the work, conducted in the 1970s, saw the dredging of 13 million cubic metres of clay and silt in the channel of Lake Saint-Pierre. Downstream of Quebec City, the water depth in the channel of the North Traverse increased from 9.1 to 12.5 m over a distance of 30 km through the excavation of 10 million cubic metres of sand and gravel. Lastly, in 1992, the channel was deepened to 11.0 metres between Montreal and Quebec City, and then to 11.3 m in 1999.

Today, the guaranteed depth in the waterway is 12.5 m downstream of Quebec City, 10.7 m between Quebec City and Deschaillons, 11.3 m to Montreal, and 8.2 in the St. Lawrence Seaway, upstream of Montreal.

Literature

Villeneuve, S. 2001. Les répercussions environnementales de la navigation commerciale. Le Naturaliste canadien 125(2): 49–67.

Villeneuve, S. and L. Quilliam. 2000. The Environmental Risks and Impacts of Navigation on the St. Lawrence River. Scientific and Technical Report ST-188E. Environment Canada – Quebec Region, Environmental Conservation, St. Lawrence Centre. 153 pages.

The Environment and Commercial Navigation on the St. Lawrence

CBC Archives – The St. Lawrence Seaway: Gateway to the world

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Date Published: 2004-12-20
Updated: 2006-07-19

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