Upcoming Gate Movements


Anglers and other users of the St. Marys Rapids are advised that on Wednesday morning, May 11, 2022, Gates #9 through #12 will be raised from their current position to a setting of 33 cm (13 in) open for the remainder of the month. Gates #9 through #12 are located near the middle of the Compensating Works structure at the head of the St. Marys Rapid on the US side of the border. Gates #7 and #8 (near the middle of the structure on the Canadian side of the border) will remain at their current setting of 20 cm (8 in). There will be no change to the setting of Gate #1, which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.

Beginning on May 11, the gate setting will be equivalent to approximately one gate fully open. These gate movements will result in an increase in the flow through the St. Marys Rapids from approximately 85 m3/s (3,000 cfs) to approximately 156 m3/s (5,500 cfs).

These gate movements are being conducted in order to achieve the Plan 2012 prescribed flow for the month. During routine maintenance and testing, mechanical problems were identified at the Canadian hydropower plant requiring urgent repairs and a reduction in flow capacity. Maximum flows are being released from the US hydropower plants to compensate for some of this difference.

It is possible that the gates will need to be raised again in June resulting in a higher flow in the St. Marys Rapids. Further changes to the gate settings will be communicated in future news releases, on the Board’s website (https://ijc.org/en/lsbc/news/releases) and on the Board’s Facebook page (https://www.facebook.com/InternationalLakeSuperiorBoardOfControl).


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: https://ijc.org/en/lsbc or on Facebook at: https://www.facebook.com/InternationalLakeSuperiorBoardOfControl