Rideau Canal National Historic Site of Canada

The History of the Rideau Canal


Specifications of the Lockstation:

One lock with a lift of five feet.

Lockmaster's house Lockmaster's house
©Parks Canada

This site's original name was First Rapids, so called because it is the first lockstation encountered in a descent toward Ottawa on the Rideau system."First Rapids" was used interchangeably with "Poonamalie" until the late 1850s, after which the latter name dominated. Tradition has it that this name is also a reflection of one of the physical characteristics of the site – an officer of the Royal Engineers who had served in India named it after a place he had seen on the subcontinent, a site with similar cedar-lined roads.

The defensible lockmaster's house at Poonamalie was built around 1842. A frame second storey was added in the late 19th century (1893).

Canal Structures:

Engineering Structures:

The one and a half mile artificial channel and lock chamber bypassed the original rapids. A natural depression was used to start the channel. The lock required no major repair during the 19th century. The dam, however, has undergone extensive repairs since the mid-1800's. This structure is of great importance because it restrains the waters of the Big Rideau and Lower Rideau Lakes, and it controls the water supply from Poonamalie to the Ottawa Locks. The dam's location at the lower end of the Rideau Lakes makes it extremely vulnerable to the heavy spring runoffs common throughout the canal. In the spring of 1869 part of the embankment at the top of the cut was washed away. Local residents helped to repair the break and navigation was soon restored. Low water levels posed a problem in 1904 when a large sheet of ice broke part of the main timber dam. When the ice broke up in the spring, instead of flowing over the dam, it struck against the back of the dam and destroyed 3/4 of the structure. The break in the dam caused damage to roads and bridges in Smiths Falls and even as far downstream as Merrickville. A new dam of concrete replaced the old timber structure.