Gate Testing at the Compensating Works Scheduled for Tuesday, September 19, 2023


Anglers and other users of the St. Marys Rapids, please be advised that testing of Gate #5 of the Compensating Works will be conducted on Tuesday, September 19. Gate #5 is located on the Canadian side of the structure, as highlighted in the figure. There will be a temporary increase in St. Marys Rapids flow while Gate #5 is temporarily raised. Once the testing is complete, Gate #5 will return to a fully closed position.

The International Lake Superior Board of Control is responsible for managing the control works on the St. Marys River and regulating the outflow from Lake Superior into Lake Michigan-Huron. Under any outflow regulation plan, the ability to regulate the flow through the St. Marys River does not mean that full control of the water levels of Lake Superior and Lake Michigan-Huron is possible. This is because the major factors affecting water supply to the Great Lakes (i.e. precipitation, evaporation, and runoff) cannot be controlled, and are difficult to accurately predict. Outflow management cannot eliminate the risk of extreme water levels from occurring during periods of severe weather and water supply conditions. Additional information can be found at the Board’s homepage: or on Facebook at: