Upcoming Gate Adjustments: Friday, June 14 through Monday, June 24, 2024
Anglers and other users of the St. Marys Rapids, please be advised that the gates of the Compensating Works at the head of the St. Marys Rapids will be adjusted multiple times in the next 11 days to facilitate underwater inspections of the International Bridge piers. During this time, outflow through the St. Marys Rapids will be temporarily reduced and the gates of the Compensating Works will be set to a one-half gate equivalent using different combinations of gates. While the one-half gate open equivalent typically flows through four gates in the middle of the Compensating Works structure, during the inspection, only two gates will be used to provide adequate safety for the inspection team. Please note that as the gates are adjusted, outflows through the St. Marys River will fluctuate and will be lower than the flows have been in the first several days of June. The flows will increase when the gates are raised again after the inspections are complete. Please take extra caution when recreating and navigating the river.
As reported in the news release issued on June 4 (https://ijc.org/en/lsbc/update-lake-superior-outflows-and-expected-conditions-june-2024), the current St. Marys Rapids flow is approximately 580 m3/s and the current gate setting is equivalent to approximately four gates fully open (Gates #7 through #14 are partially open 100 cm each). Upcoming gate changes will take place as follows:
- Friday, June 14, Gates #7 through #14 will be closed and Gates #2 and #3 will be partially opened 40 cm each. This setting will be equivalent to one-half gate open and will allow the bridge piers located in the US to be inspected.
- Thursday, June 20, Gates #2 and #3 will be closed and Gates #13 and #14 will be partially opened 40 cm each. This setting will be equivalent to one-half gate open and will allow the bridge piers located in Canada to be inspected.
- Monday, June 24, the final gate movement will be made, and the flow will increase to 628 m3/s. Gates #7 through #14 will be partially opened 108 cm and the setting will be equivalent to approximately four gates fully open.
Throughout this period, Gate #1 will remain at its typical setting, which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.
The average St. Marys Rapids flow in June is expected to be approximately 428 m3/s, to meet the Plan 2012-prescribed flow in June in consideration of the capacity restrictions at the hydropower plants.
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 management 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: https://ijc.org/en/lsbc or on Facebook at: https://www.facebook.com/InternationalLakeSuperiorBoardOfControl