Update on Lake Superior Outflows and Expected Conditions

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International-Lake-Superior-Board-Of-Control

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 3070 cubic metres per second (m3/s) for the month of August, effective August 1st. The August outflow is expected to exceed the combined capacities of the hydropower plants on the St. Marys River, which will be approximately 2280 m3/s in August, 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 in August will be decreased slightly. Gates #2 to #13 and #15 will each be lowered by 13 cm, for a total gate opening of 76 cm. This will be done in stages on Wednesday, August 5th, and on Thursday, August 6th to help facilitate flow measurements at the rapids and ensure the monthly target outflow is reached. Furthermore, inspections of the Canadian side of the Compensating Works will be conducted on August 11th and 12th, requiring further gate changes. Anglers need to be cautious of changing
flows and water levels in the rapids on each of these dates, and the unusually high flows and levels that will be experienced throughout the month.

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. Furthermore, Gate #14 will remain closed to facilitate collection of field data measurements this season, and Gate #16 will remain opened 5 cm to facilitate sea lamprey trapping.

The August outflow of 3070 m3/s is 140 m3/s more 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 expects to release flows greater than Plan 2012 in August, and less than Plan 2012 in September through November.

The monthly mean water level of Lake Superior in July was 183.68 m. This is 18 cm above the long-term (1918-2014) July average and the highest July level since 1997. The net water supplies into Lake Superior were approximately average in July. The level of Lake Superior rose 2 cm last month, less than the average rise of 4 cm in July. The Lake Superior level at the beginning-of-August is 17 cm above average, 2 cm above the level recorded a year ago at this time, and 49 cm above its chart datum level.

The monthly mean water level of Lake Michigan-Huron in July was 176.73 m. This is 16 cm above the long-term (1918-2014) July average, and the highest July level since 1998. The net water supplies to Lake Michigan-Huron were below average in July. The level of Lake Michigan-Huron was stable last month, while it typically rises 1 cm in July. The level of Lake Michigan-Huron is 16 cm above its long-term average beginning-of-August level, 26 cm higher than it was a year ago, and 72 cm above its chart datum level.

The levels of Lake Superior and Lake Michigan-Huron are both expected to begin their seasonal declines in August.

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