Gate Changes on Tuesday, June 2, 2026
Anglers and other users of the St. Marys Rapids, please be advised that Gate #14 on the U.S. side of the Compensating Works at the head of the St. Marys Rapids will be adjusted multiple times on Tuesday, June 2, 2026, to facilitate flow measurements in the St. Marys Rapids. During this time, outflow through the St. Marys Rapids will temporarily increase in increments over the course of the day, fluctuating up to 120 m3/s (4,200 ft 3/s) higher than the current flow of approximately 540 m3/s (19,100 ft3/s). Please take more caution when recreating and navigating the river, especially near the rapids.
As reported in the news release issued on May 5, 2026, the current gate setting is equivalent to four gates fully open (Gates #7 through #12 are partially open 122 cm each).
On Tuesday, June 2, in addition to Gates #7 through #12 being open, Gate #14 will be gradually opened in increments for St. Marys Rapids flow measurements. These measurements and the associated Gate #14 adjustments will take most of the day (June 2) and will produce an outflow increase from the Compensating Works of up to 120 m3/s (4,200 ft 3/s), bringing the total outflow up to approximately 660 m3/s (23,300 ft3/s) for a short time. Once the work is completed, Gate #14 will be closed and outflow through the St. Marys Rapids will return to approximately 540 m3/s (19,100 ft3/s).
Further gate adjustments for the month of June are expected to take place on Monday, June 8, 2026. Another news release will be issued on June 3 to provide the details of those movements, after the monthly computations for Regulation Plan 2012 have been completed.
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 occurring during periods of severe weather and water supply conditions. Actual flows will vary hour-to-hour and day-to-day depending on hydrologic conditions and variations in flow at the hydropower facilities. Additional information can be found on the Board’s homepage: https://ijc.org/en/lsbc.