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 (IJC), has set the Lake Superior outflow to 2600 cubic metres per second (m3/s) for the month of September, effective September 2nd.

The outflow is expected to exceed the combined capacities of the hydropower plants on the St. Marys River, which will be approximately 1908 m3/s in September, and most of the excess flow will be released through the control structure at the head of the St. Marys Rapids.

The gate setting of the control structure for the month of September will remain at the current setting equivalent to approximately four gates open, achieved by maintaining each of Gates #2 to #13 at a partially open setting of 74 cm open. Anglers need to remain cautious of the relatively higher flows and levels that will be experienced in the rapids in September. 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. Gate #14 will remain closed to allow water level measurements to be collected, and Gates #15 and #16 will also remain closed.

The September outflow is 220 m3/s less than that prescribed by Regulation Plan 2012. The Board expects to continue to adjust the outflow of Lake Superior in accordance with the approved deviation strategy to accommodate expected maintenance at the hydropower plants and reduce the potential for adverse consequences of high and fluctuating flows and water levels in the St. Marys Rapids. The Board released flows greater than Plan 2012 in June through August, and expects to release less than Plan 2012-prescribed flows in September through November.

The net water supplies to Lake Superior were above average in August. The level of Lake Superior remained at about the same level last month, while on average the lake rises 1 cm in August. The Lake Superior level at the beginning-of-September is 16 cm above average, 1 cm above the level recorded a year ago at this time, and 50 cm above its chart datum level.

The net water supplies to Lake Michigan-Huron were slightly above average in August. The level of Lake Michigan-Huron dropped 3 cm last month, while on average the lake declines 4 cm in August. The level of Lake Michigan-Huron is 28 cm above its long-term average beginning-of-September level, 10 cm higher than it was a year ago, and 80 cm above its chart datum level.

Lake Superior is expected to begin its seasonal decline in September, and the level of Lake Michigan-Huron is expected to continue its seasonal decline.

Mr. Jaymie Gadal is the Board Member for Canada. Brigadier General Mark Toy 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

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