St. Marys Rapids Flow to be Increased Tomorrow


The International Lake Superior Board of Control advises that the gate setting of the control structure at the head of the St. Marys Rapids is expected to be increased to an equivalent of three gates fully open tomorrow, Friday May 8th. This will be accomplished by opening gates #3 through #14 of the Compensating Works an additional 31 cm (12 in) for a total gate opening of 62 cm (24 in).

Anglers need to remain cautious of the changing flows and water levels in the rapids on May 8th, and the unusually high flows and levels that will be experienced thereafter. With ice remaining on Lake Superior, ice conditions also continue to pose a potential hazard. These gate movements will primarily affect water conditions in the main rapids. Gate #1, which supplies water to the channel north of the Fishery Remedial Dike, remains unchanged, and Gate #2 currently remains closed to provide lower velocities and potential angling opportunities along the northern portion of the main rapids. Gate #15 will remain closed to facilitate collection of field data measurements, and Gate #16 will remain closed until later this season, when it may be opened to facilitate sea lamprey trapping.

The Board, under authority granted to it by the International Joint Commission, increased the gate setting of the control structure to an equivalent of two gates fully open on May 1st. This gate setting was necessary to reduce the likelihood of potentially hazardous ice conditions in the St. Mary’s River. As ice conditions continue to improve, it is necessary to increase flows through the Compensating Works in accordance with the Regulation Plan 2012 and reduce the likelihood of high and fluctuating flows in the St. Marys Rapids through the summer.

The Board will continue to assess and advise on conditions as they develop.

For further information, please contact Mr. Jacob Bruxer, Canadian Regulation Representative, International Lake Superior Board of Control, by phone at (613) 938-5862 or by e-mail at [email protected]

Additional information can also be found at the Board’s homepage: