The Lachine Canal is one of Canada's National Historic Sites. It was constructed (after several false starts) in the early 1800s in order to bypass the Lachine rapids, which prevented seagoing vessels from proceeding up the St. Lawrence River past Montreal. Today it consists of scenic parkland and restorations of the original buildings and environs of the Old Port of Montreal. it is a popular tourist attraction, but the site is marred by the toxic nature of the Canal waters.
The first attempt to bypass the Lachine rapids was made by Father François Dollier de Casson, but costs proved prohibitive and the project was abandoned. Interest revived after the War of 1812, and American construction of the Erie Canal finally galvanized Montreal's businessmen into action. (In a pattern all too familiar to modern Canadians, that effort quickly failed and the government of Lower Canada has to step in.)
500 Irish workers were imported to complete the canal under the supervision of Thomas Burnett, a British engineer. Seven 1.5m (5 ft) deep locks were constructed over a total distance of 13.5 kilometres. The canal was completed in 1825.
By the 1840s, larger vessels required the locks to be enlarged, both in total length, lock area, and depth. The new project employed 1,600 Irishmen (whom were apparently thought of as some kind of badger) and deepened the locks to 2.7m (8 3/4 ft).
In the 1870s the Canal was enlarged again to handle increased traffic. (I don't know how many Irishmen this took!) Further work on the lock system continued until 1948, when the last significant work was done. The Canal was closed in 1959 when the St. Lawrence Seaway opened.
The Port of Montreal became the primary gateway between the Great Lakes and the markets of Europe and the eastern seaboard of the United States. At peak in the 1870s, almost 14,000 vessels travelled through the lock system. The system also generated hydraulic power for Montreal's industries, as well as supplying them with a waterway for coolant and the disposal of wastes.
The Canal today
Today the Canal is a National Historic Site and one of Montreal's many scenic tourist attractions. In the Old Port of Montreal, the first set of locks and some of the original buildings have been restored. Beautiful bike paths and parks have replaced the train tracks that formerly bordered the canals. Images of the park can be found at http://www.parcscanada.gc.ca/parks/quebec/canallachine/en/visite/frame_visite_e.html.
Unfortunately, access to the canals waterways for pleasure craft remains restricted, as much of the canal is dangerously contaminated. In the early 1960s, construction of Le Metro, Montreal's subway system, produced significant volumes of soil and rubble, which were unceremoniously dumped into the closed Canal. Dumping of toxic industrial sediments and raw sewage into the locks continued until the early 1980s. Despite several studies, little action has been taken to date on removing these contaminants from the Canal. Powerboats and other activities that would disturb the sediments are forbidden. Although a recent study claims that the risks are minimal, many environmentalists oppose the reopening of the Canal. A detailed discussion of the problems can be found at http://www.environmental-expert.com/magazine/hazardous/decjan1998/index.htm