We have some important hydrological news for you

NEWS RELEASE

INTERNATIONAL LAKE SUPERIOR BOARD OF CONTROL

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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 2410 cubic metres per second (m3/s) for the month of December, effective Dec. 2. The outflow is being set to the normal maximum winter flow prescribed by Plan 2012, and may at times vary due to weather events and changes in hydrologic and ice conditions.

The Board has concluded its deviation strategy (approved by the IJC on 26 April 2016) to better manage operational limitations on hydropower flow capacity, and to reduce the potential for adverse consequences of high and fluctuating flows and water levels in the St. Marys Rapids. Flows greater than Plan 2012 were released in June through August of this year, and this was followed by flows less than Plan 2012 being released in September through November.

The December outflow will be released by discharging about 2310 m3/s through the three hydropower plants and passing most of the remaining flow through the control structure at the head of the St. Marys Rapids. The gate setting of the control structure will be maintained at the equivalent of one-half gate open (four gates open 20 centimetres (cm) each) for the month of December. The one-half gate equivalent setting is the normal winter maximum, and is typically maintained from December through April. There will be no change to Gate #1, which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.

The net water supplies to Lake Superior were above average in November. The level of Lake Superior fell 4 cm last month, while on average the lake declines 5 cm in November. The Lake Superior level at the beginning-of- December is 14 cm above average, 1 cm above the level recorded a year ago at this time, and 38 cm above its chart datum level.

The net water supplies to Lake Michigan-Huron were below average in November. The level of Lake Michigan- Huron dropped 8 cm last month, while on average the lake declines 5 cm in November. The level of Lake Michigan- Huron is 22 cm above its long-term average beginning-of-December level, 4 cm higher than it was a year ago, and 56 cm above its chart datum level.

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

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