Canal Rideau

Brève description

The flight of eight locks at Ottawa Lockstation is the largest flight on the Rideau Canal. © Parks Canada Agency

Valeur universelle exceptionnelle

Le canal Rideau est un grand canal stratégique construit à des fins militaires qui a joué un rôle crucial dans la défense par les forces britanniques de la colonie du Canada contre les États-Unis d'Amérique, ce qui contribua au développement de deux entités politiques et culturelles distinctes dans le nord du continent américain ce qui peut être considéré comme une période significative de l'histoire humaine.

Critère (i) : Le canal Rideau reste l'exemple de canal en plans d'eau (slackwater canal) le mieux préservé d'Amérique du Nord, et il illustre l'utilisation à grande échelle de cette technologie européenne en Amérique du Nord. C'est le seul canal datant de la grande époque de construction de canaux en Amérique du Nord, au début du XIXe siècle, qui soit encore opérationnel sur son parcours initial et qui conserve intactes la plupart de ses structures d'origine.

Critère (iv) : Le canal Rideau est un exemple de grande envergure, bien préservé et significatif de canal utilisé à des fins militaires et illustrant une période significative de l'histoire humaine, celle de la lutte pour le contrôle du nord du continent américain.

Le bien proposé pour inscription conserve tous les éléments principaux du canal d'origine, ainsi que des modifications pertinentes apportées ultérieurement au lit du cours d'eau, aux barrages, aux ponts, aux fortifications, aux postes d'éclusage et aux ressources archéologiques associées. Le plan original du canal ainsi que la forme des canaux sont restés intacts. Le canal Rideau répond à sa fonction dynamique d'origine, celle d'être un cours d'eau praticable et ce, sans interruption depuis sa construction. La plupart de ses portes d'écluse et de ses vannes d'arrêt sont toujours actionnées par des treuils manuels.

Tous les éléments du bien proposé pour inscription (canal, bâtiments associés et forts) sont protégés en tant que sites historiques nationaux en vertu du Historic Sites and Monuments Act 1952-1953. Une zone tampon a été établie. Les réparations et la conservation des écluses, des barrages, des parois et des rives du canal sont directement réalisés sous le contrôle de l'Agence Parcs Canada. Chaque année, un tiers des installations du canal font l'objet d'une inspection exhaustive conduite par des ingénieurs. Il existe donc un inventaire complet de l'état de conservation de toutes les parties du site. Celui-ci indique que l'état de conservation de la plus grande partie du site est jugé de correct à bon. Un plan de gestion existe pour le canal (complété en 1996 et mis à jour en 2005), et des plans sont en cours de finalisation pour le fort Henry et les fortifications de Kingston. Le plan de gestion du canal est renforcé par le règlement sur les canaux historiques, qui offre un cadre d'application pour toutes les activités susceptibles d'avoir un impact sur les valeurs culturelles d'un monument.

Description historique

As a result of the American War of Independence, thousands of people who remained loyal to the British Crown moved northwards to Canada. The government immediately began identifying areas suitable for the development of settlements for the loyalists. The Cataraqui and the Rideau rivers was one of the areas surveyed and by 1800, a number of mills had been built, the first, at Kingston Mills, in 1784. Within a few years, there were mills at most of the major falls along the two rivers. However the difficulty of navigation along the rivers north to the St Lawrence river, the main settlement area, hindered much concentrated development.

The impetus to improve the waterway came though not from agriculture or other economic stimuli but from the needs of defence. The War of 1812-1814 between Britain and the United States of America had brought into focus the vulnerability of the St Lawrence River as the main supply line for the colony. Not only was it slow with a series of rapids, but it was vulnerable to attack from America along much of its length between Montréal and Lake Ontario. After the end of hostilities, America was still seen as a potential threat and the need for a secure military supply route a key necessity. Accordingly military planners turned their attention to the Cataraqui and the Rideau rivers.

After an exploratory mission, at the end of the war, the canal project was really launched in 1824-1825, with two studies, one by the civil engineer Samuel Clowes, at the request of the authorities of Upper Canada, and the other at the request of the Duke of Wellington, then commander-in- chief of the army. The strategic dimension of the canal led the British government to take charges of its realisation.

Lieutenant Colonel John By of the Royal Engineers Corp was appointed by the British Government to supervise the construction of the canal in 1826. Before his appointment, military engineers had mapped out a scheme to construct new channels to bypass the rapids and swamps along the rivers. This would have necessitated around 40km of new channels along the 202 km route. By took a different approach and persuaded the government to adopt a ‘slackwater' system that raised the level of the water above the rapids and swamps thorough the use of tall dams. This created a practical route with the minimum of excavation. By also pressed for the canal to accommodate the then newly introduced steamships and this necessitated dams that were taller and wider than anything previously constructed in North America. Canal construction begun in 1828 and involved around 6,000 workers at multiple sites along the length of the canal. The whole length was navigable in 1832.

The choice of route for the Rideau Canal, and the use of a slack water canal design, were influenced by the underdeveloped nature of the country through which the canal was to pass. In many parts of Europe, for instance, owners of riverside agricultural land, water mills and fishing rights would have resisted the alteration in river levels required by such a system. Slackwater canals are easier to build, and require fewer workers. Therefore this method will be chosen instead of a more costly conventional canal where the environment allows, as was the case with the Rideau Canal.

As with many canals, the Rideau Canal seems to have formed a catalyst for development. Ottawa grew around the canal as it runs southward from the Ottawa River, and elsewhere towns sprung up on the canal's banks. This is typical of economic development associated with canals, and mirrors the development of towns following canal building elsewhere in the world.

The Rideau Canal has survived almost in its original condition as it was by-passed following the improvement in relations between Britain and the USA and the development of the much larger St Lawrence Seaway. Its military capacity was never put to the test. It now functions mainly as a waterway for leisure craft.