With water levels well below average due a dry spring and summer, the International St. Lawrence River Board of Control will continue efforts to raise water levels on the St. Lawrence Seaway.
A dry spring and summer left the water level well below average. To address the problem the International St. Lawrence River Board of Control (Board) recently reviewed conditions in the Lake Ontario-St. Lawrence River system and will continue its strategy of responding to the dry conditions experienced since last spring.
The Board will continue to over-discharge relative flows to maintain minimum water levels in the Montreal area.
However, conditions have recently allowed the board to release flows less than those specified by the regulation plan, in order to restore Lake Ontario to its plan-specified level. This will continue as opportunities permit.
The lake is currently about 1 cm (0.4 in) below its plan-specified level.
The level on Lake Ontario as of Dec. 11 was 74.26 m (243.64 ft), 11 cm (4.3 in) above the lower limit that applies from April 1 to November 30, but 27 cm (10.6 in) below the average level for this time of year. The level at the Port of Montreal on Dec. 11 was 5.51 m (18.1 ft), 103 cm (41 in) below average.
The level in Montreal has fallen about 30 cm (12 in) in the past month, and through the first two weeks of December levels have been below the previous record monthly mean level for this month.
The Board, in conjunction with its staff, continues to monitor the situation carefully and is prepared to take further action as required.
The Board will continue to review conditions and revise the outflow strategy, if necessary. Outflow changes are posted to the Board’s Facebook site at www.facebook.com/ISLRBC (English) and its website at http://ijc.org/conseil_board/islrbc/en/data_informations.htm under Lake Ontario outflow changes.
Water levels on both Lake Ontario and the St. Lawrence River vary considerably from year to year depending on the weather conditions.
The Board urges everyone to be prepared to live within the full range of levels that have occurred.
Although the Board strives to maintain the range of monthly mean levels of Lake Ontario below the upper limit of 75.37 m (247.3 ft) and above the lower limit (from April through November) of 74.15 m (243.3 ft) specified in the Orders of Approval, since regulation began in 1960, actual monthly levels have ranged from a high of 75.74 m (248.5 ft.) to a low of 73.82 m (242.2 ft) due to climate conditions outside the design range.
Levels on the river tend to vary more widely. Furthermore, excessive wind set up and wave action may significantly increase or decrease local levels on both the lake and river. Strong winds can change water levels temporarily by over half a meter (2 feet) in some locations.