Why the Lower St. Marys will get lower this month

The International Lake Superior Board of Control has advised that water levels on the Lower St. Marys River will be reduced on two days this month because they'll be cutting outflows through the hydropower plants in both the Michigan and Ontario Saults.

The following is the official announcement:

*************************** Lake Superior outflow conditions

The International Lake Superior Board of Control, under the authority granted to it by the International Joint Commission, has set the Lake Superior outflow to 2,380 cubic meters per second (m3/s) (84.0 thousand cubic feet per second (tcfs)) for the month of October.

This is the outflow recommended by the regulation plan for the month of October and is an increase from the September outflow of 2,350 m3/s (83.0 tcfs).

The October outflow will be released by discharging about 2,256 m3/s (79.7 tcfs) 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 existing setting equivalent to one-half gate open (four gates open 25 cm, or about 10 inches each).

There will be no change to the setting of Gate #1 that supplies the Fishery Remedial Works.

The International Lake Superior Board of Control would also like to make people aware that the outflows through the hydropower plants at Sault Ste. Marie will be reduced on several days in October.

The flow through the Great Lakes Power Limited plant will be stopped for several hours on October 9th beginning in the morning to allow a safety inspection of underwater cables and the highway bridge piers.

The flow through the Edison Sault Electric Company plant will continue to be reduced during the day from October 1st to 8th to permit maintenance work in their power canal.

These actions will not affect flows in the St Marys Rapids, but will result in water levels in the lower St Marys River being lower than they would otherwise be during these periods.

The water supply to Lake Superior this past month was greater than average for September, while the supply to Lakes Michigan-Huron was less than average for September. Currently, the Lake Superior level is about 10 cm (4 inches) below its long-term average beginning of October level but is 15 cm (6 inches) above the level recorded a year ago.

This past month the level of Lake Superior rose by 1 cm (0.5 inches), while it usually declines by 1 cm (0.5 inches) during September.

The level of Lakes Michigan-Huron declined by 10 cm (4 inches) this past month, which is more than the usual 6 cm (2 inches) decline for September.

The level of Lakes Michigan-Huron is now about 29 cm (11 inches) below its long-term average beginning of October level, but is now 31 cm (12 inches) higher than a year ago.

The Board continues to monitor conditions both on Lake Superior and downstream and will advise the International Joint Commission accordingly on those conditions.

Brigadier General Steven R. Hawkins, Commander, Great Lakes and Ohio River Division, U.S. Army Corps of Engineers, is the United States Board Member.

Mr. Carr McLeod is the Board Member for Canada.

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