International Lake Superior Board of Control

ST. MARYS RAPIDS FLOW TO BE INCREASED TOMORROW

2014/05/14

The International Lake Superior Board of Control advises that the gate setting of the control structure at the head of the St. Marys Rapids is expected to be increased to an equivalent of five gates fully open tomorrow, Thursday, May 15th

Anglers need to remain cautious of the changing flows and water levels in the rapids on May 15th, and the unusually high flows and levels that will be experienced thereafter.  With ice remaining on Lake Superior, ice conditions also continue to pose a potential hazard.  The gate movements will primarily affect water conditions in the main rapids, but with the equivalent of five gates fully open in the control structure, water may overtop the Fishery Remedial Dike along the north side of the Rapids, and may create a hazard.  There will be no change to the setting of Gate #1, which supplies water to the channel north of the Fishery Remedial Dike. 

The Board, under authority granted to it by the International Joint Commission, increased the gate setting of the control structure to four gates fully open on May 5th.  This was necessary to achieve the total prescribed May outflow from Lake Superior, and to reduce the risk of unusually high outflows expected in the summer months.  However, as a result of potentially hazardous ice conditions observed in the St. Marys River, the flow and gate setting was temporarily reduced as a precaution on May 6th.  As ice conditions stabilized, fourteen gates were partially re-opened the following day, May 7th, to a setting equivalent to approximately three gates fully open. 

Ice conditions have since continued to improve.  The increased gate setting scheduled for Thursday will help offset the lower flows experienced during the first half of May.  Lake Superior’s water level has already risen approximately 13 cm (5.1 in.), more than the average 10 cm (3.9 in.) the lake rises in May.  As a result of these wetter than normal conditions, the Board expects that the gate setting will continue to be five or more gates during the month of June. 

The Board will continue to assess and advise on conditions as they develop.