Board awaits downstream snowmelt
The International St. Lawrence River Board of Control (Board) recently reviewed conditions in the Lake Ontario-St.Lawrence River system and has agreed to continue to follow the Regulation Plan at this time. However, the Board also decided to store water on Lake Ontario for future critical needs when downstream conditions permit. Additional water may be stored during the freshet period to prevent flooding downstream in the Lake St. Louis area.
Lake Ontario is currently at its plan-specified level, but is below its long term average, as are the other Great Lakes. Under-discharge will begin when the level on Lake St. Louis at Pointe Claire reaches 21.8 m (71.5 ft), 30 cm (1 ft) lower than the flood alert level. The Board will begin to store up to 5 cm (2 in) of water on Lake Ontario, but will stop storing water if the level at Pointe Claire falls below 21.6 m (70.9 ft). The Board will store in excess of 5 cm (2 in) only if the level on Lake St. Louis is at risk of exceeding the flood alert level of 22.1 m (72.5 ft). This strategy will allow the Board to address uncertainty in the inflows during the freshet period. In addition, while the strategy will provide environmental and recreational benefits of higher water levels upstream on Lake Ontario, the extra water stored can also be released later in the season to benefit commercial navigation and boaters in the lower St. Lawrence River. At the Board’s next teleconference, a decision will be made whether to retain the stored water on Lake Ontario for gradual release over a possibly dry summer and fall, or to release the extra water earlier, in response to possibly wetter conditions.
The level on Lake Ontario as of April 17 was 74.76 m (245.28 ft), 61 cm (24.0 in) above the lower limit that applies from April 1 to November 30, but 13 cm (5.1 in) below the long term average level for this time of year. The level on Lake St. Lawrence as of April 17 was 73.73 m (241.90 ft), which is currently above average due to lower than average outflows through the Moses-Saunders dam. The level at the Port of Montreal on April 17 was 6.77 m (22.2 ft), 75 cm (29.5 in) below average.
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 https://www.facebook.com/InternationalLakeOntarioStLawrenceRiverBoard and its website at www.ijc.org/loslrb under Lake Ontario outflow changes.
Water levels on bothLakeOntarioand theSt. Lawrence Rivervary 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 75.73 m (248.5 ft.) to a low of 73.83 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 metre (2 feet) in some locations.
Contacts:
Gail R. Faveri: (905) 336-6007; gail.faveri@ec.gc.ca
John Kangas: (312) 353-4333; John.W.Kangas@usace.army.mil
The International St. Lawrence River Board of Control was established by the International Joint Commission in its 1952 order of approval. The Board’s main duty is to ensure that outflows from Lake Ontario meet the requirements of the IJC order; it also develops regulation plans and conducts special studies requested by the IJC. For more information, visit www.ijc.org/loslrb. To receive a weekly e-mail about water levels and flows in the Lake Ontario–St. Lawrence River system, please send a blank e-mail message to stlaw-L-subscribe@cciw.ca, with the word ’subscribe’ in the title and body of your message.