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 3300 cubic metres per
second (m3/s) for the month of July, effective July 3rd. There will be no change to the current
setting of the control structure at the head of the St. Marys Rapids.
The outflow of Lake Superior continues to be adjusted over the next several months to reduce the
risk of unusually high flows expected in the St. Marys Rapids this summer. The Board requested
and received approval from the IJC to temporarily deviate from Lake Superior Regulation Plan
1977-A to allow for these adjustments. On 25 June 2014, the gate setting of the control structure
at the head of the St. Marys Rapids was increased to the current setting equivalent to seven gates
open (achieved by setting 14 gates to a partially open setting of 94 centimetres (cm) each). This
setting is expected to be maintained for the month of July, and as a result, the July outflow will be
160 m3/s less than the amount specified by Plan 1977-A.
The monthly mean water level of Lake Superior in June was 183.60 m. This is 16 cm above the
long-term (1918-2013) June average and the highest June level since 1997.
This past month the net water supplies to Lake Superior were above average. The level of Lake
Superior rose 9 cm last month, while on average the lake rises 8 cm in June. The Lake Superior
level at the beginning-of-July was 15 cm above average, and 31 cm above the level recorded a
year ago at this time. It is 43 cm above its chart datum level. The level of Lake Superior is
expected to continue its seasonal rise during July.
The monthly mean water level of Lake Michigan-Huron in June was 176.38 m. This is 16 cm
below the long-term (1918-2013) June average, but the highest June level since 2009.
The net water supplies to Lake Michigan-Huron were also above average in June. The level of Lake
Michigan-Huron rose 11 cm this past month, while on average the lake rises 6 cm in June. The
level of Lake Michigan-Huron is 12 cm below its long-term average beginning-of-July level, but
36 cm higher than it was a year ago. Lake Michigan-Huron is now 44 cm above its chart datum
level. The level of Lake Michigan-Huron is also expected to continue its seasonal rise in July.
Mr. Jaymie Gadal is the Board Member for Canada. Ms. Deborah Lee is the Alternate U.S. Board
Member.
