UPDATE ON LAKE SUPERIOR OUTFLOWS AND EXPECTED CONDITIONS - OCTOBER 2017
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 3,130 cubic metres per second (m3/s) for the month of October, effective October 3rd. The October outflow is as prescribed by Regulation Plan 2012 and is expected to exceed the combined capacities of the hydropower plants on the St. Marys River, which will be approximately 2,122 m3/s in October. Most of the remaining flow will be released through the control structure at the head of the St. Marys Rapids.
The gate setting of the control structure was increased yesterday from the previous setting equivalent to approximately five gates open to a setting equivalent to approximately six gates open. This was achieved by partially opening each of Gates #2 through #15 to a setting of 94 cm open. There will be no change to the setting of Gate #16 or the setting of Gate #1, which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.
The average St. Marys Rapids flow in October will be approximately 994 m3/s. Conditions will be similar to those seen during the summer of 2014. Therefore, anglers and other users of the St. Marys Rapids need to remain cautious of the high and changing flows and water levels that will be experienced in the rapids in October. Flooding of low-lying areas of Whitefish Island is expected to continue this month and some recreational trails and features in these areas will be inundated. Users are encouraged to use extreme caution.
The net water supplies to Lake Superior were above average in September. The level of Lake Superior rose 2 cm last month, while on average the lake declines 2 cm in September. The Lake Superior level at the beginning-of-October is 29 cm above average, 10 cm above the level recorded a year ago at this time, and 61 cm above its chart datum level.
The net water supplies to Lake Michigan-Huron were below average in September. The level of Lake Michigan-Huron fell 8 cm last month, while on average the lake declines 6 cm in September. The level of Lake Michigan-Huron is 42 cm above its long-term average beginning-of-October level, 16 cm higher than it was a year ago, and 88 cm above its chart datum level.
The level of Lake Superior is expected to begin its seasonal decline in October, and the level of Lake Michigan-Huron is expected to continue its seasonal decline.