The Rideau Canal, a monumental early 19th-century construction covering 202 km of the Rideau and Cataraqui rivers from Ottawa south to Kingston Harbour on Lake Ontario, was built primarily for strategic military purposes at a time when Great Britain and the United States vied for control of the region. The site, one of the first canals to be designed specifically for steam-powered vessels, also features an ensemble of fortifications. It is the best-preserved example of a slackwater canal in North America, demonstrating the use of this European technology on a large scale. It is the only canal dating from the great North American canal-building era of the early 19th century to remain operational along its original line with most of its structures intact.
The flight of eight locks at Ottawa Lockstation is the largest flight on the Rideau Canal.
© Parks Canada Agency
Outstanding Universal Value
The Rideau Canal is a large strategic canal constructed for military purposes which played a crucial contributory role in allowing British forces to defend the colony of Canada against the United States of America, leading to the development of two distinct political and cultural entities in the north of the American continent, which can be seen as a significant stage in human history.
Criterion (i): The Rideau Canal remains the best preserved example of a slackwater canal in North America demonstrating the use of European slackwater technology in North America on a large scale. It is the only canal dating from the great North American canal-building era of the early 19th century that remains operational along its original line with most of its original structures intact.
Criterion (iv): The Rideau Canal is an extensive, well preserved and significant example of a canal which was used for a military purpose linked to a significant stage in human history - that of the fight to control the north of the American continent.
The nominated property includes all the main elements of the original canal together with relevant later changes in the shape of watercourses, dams, bridges, fortifications, lock stations and related archaeological resources. The original plan of the canal, as well as the form of the channels, has remained intact. The Rideau Canal has fulfilled its original dynamic function as an operating waterway without interruption since its construction. Most of its lock gates and sluice valves are still operated by hand-powered winches.
All the elements of the nominated area (canal, associated buildings and forts) are protected as national historic sites under the Historic Sites and Monuments Act 1952-3. A buffer zone has been established. Repairs and conservation of the locks, dams, canal walls and banks are carried out directly under the control of Parks Canada. Each year one third of the canal's assets are thoroughly inspected by engineers. A complete inventory thus exists of the state of conservation of all parts of the property. A Management Plan exists for the canal (completed in 1996 and updated in 2005), and plans are nearing completion for Fort Henry and the Kingston fortifications. The Canal Plan is underpinned by the Historic Canals Regulations which provide an enforcement mechanism for any activities that might impact on the cultural values of the monument.
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. Source: Advisory Body Evaluation