Drawdown is guided by research, engineering and decades of experience.
Drawdown is when water levels are lowered in the Rideau Canal.
It's a complex process that takes into consideration storage capacity of the lakes on the system, timing of fishery spawning, requirements for flood mitigation, typical fall and winter precipitation levels, downstream typography including constrictions like narrow river beds or dams, and overall volumes and flow rates.
From mid-October until mid-November, water levels in the Rideau Canal system, between Ottawa Locks and Burritt’s Rapids, will be decreased to winter storage levels by adjusting dams and spillways in the Lower Rideau Watershed in order to prepare for freeze up and to reduce the possibility of spring flooding. The following Rideau Canal sections will be affected:
- Water levels will be decreased in the sections below Hog's Back, including Dow's Lake, beginning Monday, October 9, 2017 and will remain at their lowest level until mid-November, after which the water level will then be raised approximately one metre between Hartwells and Ottawa lockstations to prepare for the Skateway.
- Water levels will be lowered between Hog's Back to Black Rapids beginning Tuesday, October 10, 2017.
- Water levels will be lowered between Long Island to Black Rapids beginning Tuesday, October 10, 2017.
- Water levels will be lowered between Burritt's Rapids to Long Island beginning Monday, October 30, 2017.
Parks Canada encourages the public to use caution in and around canal structures and channels over the winter months. From mid-October to the end of May, the canal’s lock stations are closed and use of the canal is at one’s own risk. Unmarked hazards may exist. Wet leaves, ice, and snow may remain on stairs and walkways, and ice conditions on the waterway can vary. Boaters are advised that during the non-navigation season, aids to navigation may be missing, off-station, or inoperable until next spring.