1. Context

1.2 The Historic Context

Although the idea of creating a navigable corridor on the Richelieu River had attracted the attention of colonial authorities since the late 18th century, the riverbed was not dug out until 1829, and the dredging of the canal continued until 1831. Nevertheless, it was recommended in 1835 that a dam and lock of cut stone be built downstream from Darvard Island. The urgent need to work on the Chambly section first meant that work did not begin until 1844. Consulting newly available studies, the authorities picked a different site from the one originally chosen (660 metres upstream from Darvard Is-land4)—whence the works on each side of the island still visible today.

The construction at Saint-Ours constituted an essential element of the international potential of the Richelieu corridor, as it formed part of the link between the St. Lawrence and Hudson River valleys. As with the Chambly Canal, the Saint-Ours lock witnessed a steady stream of boats carrying wood from New England and later, from the Ottawa River valley, as well as coal from Pennsylvania. Canadian commodities and American products passed through Saint-Ours into the larger international trade network. The size of the lock, bigger than the one at Chambly, guaranteed that exports could access the Chambly Basin. Saint-Ours also played a major role in trade between local parishes and the major urban centres of Montreal, Québec and Trois-Rivières.

The imposing building on the east side of the lock is a flourmill built by the seigneurs of Saint-Ours around the time of the construction of the first lock.
The lower entrance to the Saint-Ours Canal, 1907
© Parks Canada / neg. 161/00/ic-7/1907

The structures at Saint-Ours were built in several phases, and the whole system was not completed for another 125 years. The first structures were undertaken between 1844 and 1849, and included a cut stone lock 61 metres long by 13.7 metres wide and drawing 1.6 metres of water, as well as two dams, one on each arm of the river. The arm running between the west bank and the island was blocked by a 183-metre-long dam made of stone-filled cribwork, while the dam crossing the eastern arm next to the lock was a 92-metre-long earthwork construction. This earthwork dam was connected to a discharge channel that fed a flourmill built in 1845-1846 by the seigneurial family of Saint-Ours. In 1851, improvements deepened the lock to a depth of 2.1 metres at gate sill level. The lock henceforth enabled craft to negotiate a 1.5-metre change in elevation.

The lock was repaired on various occasions between 1852 and 1857. This period is notable mainly for the construction of the superintendent’s residence, including a row of attached buildings (1854-1855), and by the reinforcement of the dam and its eastern abutment.

From 1868 to 1929, the site was progressively altered. The aprons and upper and lower lock sills were upgraded periodically. Almost every year, tons of stone were dumped to reinforce the dam, its abutments and the river banks. In 1882-1883, wooden caissons were built on the eastern side of the lock, both upstream and downstream. From 1885 to the early 1900s, numerous repairs projects led to the construction on the island of several buildings that were needed for canal operations. Between 1908 and 1913, the site and the gate mechanisms were electrified.

To remedy a cyclical problem of water shortage above the dam, a mobile triangular crest was built in 1911 atop the dam apron. This could be used to raise the water level upstream by two feet during the dry season.

Between 1930 and 1933, major work was undertaken that resulted in the present-day lock structures. This work was undertaken in response to a desire to integrate with American canal navigation, which had reached a new scale in 1918 with the building of locks in New York State that allowed the passage of 900-ton barges. Standardization began from 1928 to 1930 with the dredging of the Richelieu River between Sorel and Saint-Ours.

Work included the building of a new 103.3-metre-long concrete lock with a standard draught of 3.7 metres, the cutting of a 0.2-km canal and the installation of a new lighting system. The upper entrance of the old lock was filled in and the lower entrance left open so that it could be used as a basin.

In 1966, work on the construction of a 180-metre-long dam was begun to replace the dam on the western side of the island. The new dam, unique in North America, was fitted with five v-shaped sluice gates that regulate the water level of the Richelieu River all the way to the Chambly Basin. However, the new plans did not incorporate a fish ladder, which had been part of the western dam since about 1891. This omission was rectified in 2000.

During the 1960s and until 1972, many noticeable changes were made to the properties and buildings along the Saint-Ours Canal, such as the building of the current lock-master’s shelter and the control sheds, the addition of garages, the reshaping of the eastern bank to its current form, the filling in of the entire first lock, and the integration of the underground storage area for stoplogs, as well as the demolition of the old control stations on the island and of the outbuildings of the superintendent’s home.

4 It was known as Duchesnay Island, the name of its owner, before it was sold so as to permit works to begin. Sévigny, André P. Navigation et canalisation dans le Bas-Richelieu au milieu du dix-neuvième siècle : l’écluse et le barrage Saint-Ours [published in English as: St. Ours and Navigation on the Lower Richelieu River in the Mid-Nineteenth Century (Research Bulletin)]. Parks Canada, 1983. 385 pages, p. 55.

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