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 3080 cubic metres per second (m3/s) for the month of July, effective July 1st. The July outflow is expected to exceed the combined capacities of the hydropower plants on the St. Marys River, which will be approximately 2255 m3/s in July, 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 July will be increased in stages to help facilitate flow measurements at the rapids and ensure the monthly target outflow is reached. Anglers need to be cautious of changing flows and water levels in the rapids on July 6th and on July 14th, and the unusually high flows and levels that will be experienced throughout the month. Gate #2, which is currently closed, will be partially opened 71 cm next Monday, July 6th. On July 14th, Gates #2 to #13 and Gate #15 will be opened an additional 23 cm for a total gate opening of 94 cm. 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 July outflow of 3080 m3/s is 130 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 July and August, and less than Plan 2012 in September through November.
The monthly mean water level of Lake Superior in June was 183.63 m. This is 19 cm above the long-term (1918-2014) June average and the highest June level since 1997. The net water supplies into Lake Superior were above average in June. The level of Lake Superior rose 8 cm last month, which is the average rise in June. The Lake Superior level at the beginning-of-July is 19 cm above average, 4 cm above the level recorded a year ago at this time, and 47 cm above its chart datum level.
The monthly mean water level of Lake Michigan-Huron in June was 176.68 m. This is 14 cm above the long-term (1918-2014) June average, and the highest June level since 1998. The net water supplies to Lake Michigan-Huron were above average in June. The level of Lake Michigan-Huron rose 8 cm last month, while on average the lake rises 5 cm in June. The level of Lake Michigan-Huron is 17 cm above its long-term average beginning-of-July level, 28 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 continue their seasonal rise in July.
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 Jacob.Bruxer@ec.gc.ca
Additional information can also be found at the Board’s homepage: http://ijc.org/en_/ilsbc