IJC Raises St Lawrence Level for Boaters
October 23, 2025
The International Lake Ontario-St. Lawrence River Board temporarily increased the outflow from Lake Ontario on October 18 to help raise the water level on the St. Lawrence River to assist with boat haul-outs on Lake St Louis. This action was taken to address low water levels caused by drought conditions.
- Why the levels were raised:
To assist with end-of-season recreational boat haul-outs on the St. Lawrence River, which were being hampered by unusually low water levels.
- How it was done:
The Board temporarily increased the outflow from Lake Ontario by up to 500cubic meters per second for about 36 hours, a decision permitted under its “minor deviation authority”.
- Impact: The increased outflow was expected to raise water levels on Lake St. Louis by about 15 cm to help with the boat removal process. This action was not expected to have a significant adverse effect on Lake Ontario’s level.
The International Lake Ontario-St. Lawrence River Board ensures that outflows from Lake Ontario meet the requirements of the International Joint Commission’s Orders of Approval.
Under any regulation plan, the ability to regulate the outflow from Lake Ontario does not mean that full control of lake levels is possible. This is because the major factors affecting water supply to the Great Lakes – precipitation, evaporation, and runoff – cannot be controlled, and are difficult to accurately predict.
