Update on Lake Superior Outflows and Expected Conditions

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The International Lake Superior Board of Control, under authority granted to it by the International Joint Commission, has set the Lake Superior outflow to 2400 cubic metres per second (m3/s) for the month of April, effective April 4th. The April outflow is expected to exceed the combined capacities of the hydropower plants on the St. Marys River and the excess flow will be released through the control structure at the head of the St. Marys Rapids.

There is minimal ice cover remaining on either Lake Superior or the St. Marys River upstream of the control structure, and this will allow the gate setting of the control structure to be increased to an equivalent of approximately one gate open in April. The one-gate equivalent setting will be achieved by partially opening each of Gates #2 through #16 to a setting of 20 cm on Wednesday, April 6th, with the exception of Gate #14, which will remain closed to allow water level measurements to be collected. Employing partially open gates will prevent any remaining ice from passing through the gates and reduce the risk of ice-related issues, and will also more evenly spread the flow of water across the width of the main rapids. 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.

The net water supplies to Lake Superior were above average in March. The level of Lake Superior remained stable last month, while on average the lake falls 1 cm in March. The Lake Superior level at the beginning-of-April is 25 cm above average, 6 cm above the level recorded a year ago at this time, and 28 cm above its chart datum level. The level of Lake Superior is expected to begin its seasonal rise during April.

The net water supplies to Lake Michigan-Huron were also above average in March. The level of Lake Michigan-Huron rose 14 cm last month, while on average the lake rises 4 cm in March. The level of Lake Michigan-Huron is 39 cm above its long-term average beginning-of-April level, 22 cm higher than it was a year ago, and 70 cm above its chart datum level. The level of Lake Michigan-Huron is expected to continue its seasonal rise during April.

Mr. Jaymie Gadal is the Board Member for Canada. Brigadier General Richard Kaiser is the U.S. Board Member.

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: http://ijc.org/en_/ilsbc
Or on Facebook at: https://www.facebook.com/InternationalLakeSuperiorBoardOfControl