Why lower the canal water?
The canals for which Parks Canada is responsible are national historic structures. As manager of the sites, the Agency operates the canals and performs conservation work on their infrastructures. These investments in the preservation, rehabilitation and restoration of national historic sites help to protect our heritage and strengthen their appeal as destinations to celebrate our nation’s achievements.
It is primarily for maintenance and restoration purposes that Parks Canada must occasionally empty the Lachine Canal. Lowering the water allows technicians to examine and perform maintenance on components that are key to safely operating the locks.
A delicate operation
In most cases, we lower the canal water right after the navigation season, in October. In general, we avoid leaving the canal empty during the winter, as the body of water alone plays a key role in maintaining the canal. In fact, the body of water makes it possible to offset the force exerted by the earth on the walls outside the foundations of the canal, particularly in freezing conditions. However, since 2017, the canal has had to remain empty during the winter for extensive rehabilitation work on its walls.
A huge undertaking
Making millions of cubic metres of water disappear is no small feat! First, all wharves attached to walls in the lock chambers and along the canal must be removed. Then, we open the valves one at a time, starting with the lock furthest downstream and moving toward the lock furthest upstream. Emptying the Lachine Canal can take two to three days!
What about the fish?
It’s the major question we all ask ourselves when we undertake this type of operation. Rest assured that most fish pass through the valves of the locks and reach the river. However, some of them may get caught in pockets of water, which are generally deep enough to ensure their survival through winter. When a section of the Canal is completely dry, the Parks Canada environmental teams get involved by collecting fish and releasing them into the nearest watercourse, as seen in the video below filmed at Chambly Canal.