The St. Lawrence Seaway

After 1825, ships could take the Lachine Canal to bypass the rapids and continue up the St. Lawrence. In the mid-19th century, ships with a draft up to 2.7 m could reach Lake Erie by taking the Beauharnois (1845), Cornwall (1843) and Welland (1829) Canals. Commercial ships grew larger and larger over time and the existing locks and canals eventually became too small for them to pass. In 1895, the first joint U.S. - Canadian Deep Waterways Commission assessed the feasibility of building a seaway. An International Joint Commission followed in 1909, but it was not until 23 years later that Canada and the United States would sign the Great Lakes-St. Lawrence Deep Waterway Treaty. In 1951, the two countries began to work together on the project. Canada passed two acts authorizing the construction of infrastructure to enable navigation from Montreal to Lake Ontario and on the Welland Canal and the construction of hydroelectric facilities in the International Rapids section of the St Lawrence. The U.S. government also approved work on the Wiley-Dondero Canal to bypass the International Rapids.

Today, the Great Lakes St. Lawrence Seaway System, branded as "Highway H₂O," features five canals and 15 locks. This remarkable feat of engineering raises and lowers ships a total of 183 m between the Atlantic Ocean and Lake Erie.

Click HERE to see the locations of the various locks of the St. Lawrence Seaway.

The South Shore Canal features the St. Lambert Lock downstream and the Côte Ste. Catherine Lock upstream. It runs 25.9 km, bypassing the Lachine Rapids. Next, the Beauharnois Canal with its two locks links Lake Saint-Louis and Lake Saint Francis over a distance of 20.9 km. To the west, after Lake Saint Francis, the international portion of the Seaway begins as it passes under the bridge between Cornwall, Ontario and Massena, New York. This toll bridge is jointly managed by the Federal Bridge Corporation Limited (Canada) and the Saint Lawrence Seaway Development Corporation (United States). Ships then enter the American Wiley-Dondero Canal with its Snell (downstream) and Eisenhower (upstream) Locks. This 16-km long canal provides access to Lake St. Lawrence, bypassing the international Moses-Saunders Power Dam. Further west, the Seaway crosses back into Canada and bypasses the Iroquois Dam via the Iroquois canal, just 0.6 km long, and its lock. The lock adjusts traffic to the water level of Lake Ontario with a lift that varies between 0.6 and 1.8 m.

The Welland Canal enables ships to pass from Lake Ontario to Lake Erie, ascending the Niagara Escarpment and bypassing the enormous waterfalls. It is 43.5 km long and includes eight locks. Locks 1 to 7 have the largest lift. Lock 8, not far from Port Colborne on Lake Erie, is used to adjust the water level to that of Lake Erie and has a shallow lift between 0.3 and 1.2 m.

Starting in 1895, it was possible to navigate from the Atlantic all the way to Lake Superior using the canal and lock at Sault Ste. Marie, on the Canadian side of the St. Marys River. Nowadays, the canal and lock are only used for recreational boating, while larger commercial ships transit via the Poe Canal on the U.S. side, built in 1968. In the U.S. portion of the St. Marys, there are two parallel locks (Sabin and Davis) on the north canal and two more (Poe and MacArthur) on the south canal. The Sabin Lock has been decommissioned, while the Davis Lock, built in 1914, is seldom used. The MacArthur Lock, built in 1943, can only accommodate ships up to 223 m long. The commercial locks of Sault Ste. Marie, known as the Soo Locks, are operated by the U. S. Army Corps of Engineers.

The Welland Canal runs from Port Colborne on Lake Erie down to Port Weller on Lake Ontario. In 1824, the merchant William Hamilton Merritt used public and private funds to found the Welland Canal Company. He wanted to dig a canal primarily to bring water to his mills. Feasibility studies were conducted, then the first channel and locks were built between 1829 and 1844. Extensive improvements to the locks were later carried out, and the canal was widened. A second canal was built between 1845 and 1886. A third canal was completed between 1887 and 1931. Construction on a fourth canal began in 1913, but was unfortunately suspended until 1919 because of World War I. The canal was finally completed in 1932. This fourth Welland Canal is the last to have been built.

Locks 1 to 7 on the Welland Canal raise and lower ships a total of 99.5 m. Each lock has a rise of 14.2 m. Locks 4, 5 and 6 are particularly impressive because they are very close together and resemble a giant staircase. They enable ships to quickly bypass most of the Niagara Escarpment—a cliff that crosses the region, giving rise to Niagara Falls. These locks are twinned to accelerate traffic, allowing ships to transit in different directions at the same time. It takes between 1.5 and 2.5 hours to transit through the three locks.

When the Seaway was built, some adjustments had to be made to allow road and railway bridges to cross the river. A notable case is the St. Lambert Lock, at the southern end of the Victoria Bridge. An ingenious diversion system, featuring a lift span on each end of the lock, was devised to allow trains and vehicles to circulate during lockage operations.

The 15 locks along the Seaway are each 233.5 metres long, 24.4 m wide and 9.1 m deep. To transit the locks, ships can be up to 225.5 m long and 23.8 m wide. Their draft must not exceed 8.08 m. Each lock contains around 91 million litres of water, the equivalent of 25 Olympic swimming pools. The locks are filled and emptied by gravity in less than 10 minutes. It takes approximately 45 minutes for a ship to transit through a lock.

The completion of the Great Lakes St. Lawrence Seaway opened the Great Lakes region to global markets. On April 25, 1959, the icebreaker D'Iberville began the first full transit at the St. Lambert Lock. The official opening ceremonies were held on June 26 that same year. Queen Elizabeth II arrived at the St. Lambert Lock aboard the Royal Yacht Britannia, along with U.S. President Dwight D. Eisenhower and Canadian Prime Minister John G. Diefenbaker. On June 27, another ceremony took place in Massena, New York, with the Queen in attendance. Since the President was unable to attend, he was represented at the event by his Vice-President Richard M. Nixon.

In 1952, the Joint International Commission approved the construction of a hydroelectric dam between Cornwall, Ontario and Massena, New York. In 1956, the governments of Canada and the United States gave their support to the project while imposing certain requirements. Water levels in Lake Ontario had to be controlled to provide dependable flow for hydroelectric power, maintain adequate depths for safe navigation, and protect the shoreline and other interests downstream in Quebec.

To enable the project to go ahead, an expropriation process was initiated in 1954. Around 550 houses were relocated and some 6,500 people were moved to new homes. An area of 259 km² was flooded, creating an artificial lake known as Lake St. Lawrence. This reservoir still supplies the international Moses-Saunders Power Dam downstream of the lake. The water flow spins the turbines of the power station.

In May 1958, the Iroquois Lock upstream of Lake St. Lawrence became operational. The Snell and Eisenhower Locks on the Wiley-Dondero Canal, not far from Massena, were inaugurated that June. The international Moses-Saunders power station was then able to begin generating electricity.

The Wiley-Dondero Canal replaced the old Cornwall Canal built between 1834 and 1842 to bypass the rapids of Long Sault. This canal had been enlarged several times between 1876 and 1904.

After crossing Lake St. Lawrence, ships transit through the Iroquois Lock to reach the beautiful Thousand Islands region.

Every year, over 2,000 pleasure craft transit through the Seaway. To pass through the locks, boats must have a motor, be at least 6 m long and weigh at least 900 kg.

On the western end of Lake Saint-Louis, ships enter the two Beauharnois Locks, which bypass the Hydro-Québec power station. Each lock raises ships around 12.5 m, to the level of the Beauharnois Canal leading to Lake Saint Francis. They can then proceed through the lake along dredged channels.

In 1998, day-to-day management of the Canadian portion of the Seaway was transferred from the St. Lawrence Seaway Authority to the St. Lawrence Seaway Management Corporation, a new non-profit corporation. The infrastructure still belongs to the Government of Canada, which also remains responsible for regulations.

The St. Lambert Lock is the first lock encountered by ships headed upstream on the St. Lawrence Seaway. The shipping channel starts just east of the Jacques Cartier Bridge. When the Seaway was built, the section of the bridge that crosses it had to be elevated by 15.2 m to allows enough clearance for ships. Once they pass beneath the bridge, ships continue another 4.8 km before reaching the St. Lambert Lock.