While water level conditions in Lake Ontario have changed as a result of heavy rains this past week from Hurricane Sandy, government overseers of water levels in the lake and St. Lawrence River system have elected to stick with their earlier plans.
The International St. Lawrence River Board of Control recently reviewed conditions in the Lake Ontario-St. Lawrence River system and decided to continue to moderately over-discharge relative to plan-specified flows when necessary to maintain adequate minimum water levels in the Montreal area. When conditions downstream permit, the board will reduce outflow to restore water back to Lake Ontario, relative to Plan 1958-D, as soon as possible.
The level on Lake Ontario as of Oct. 17 was 74.32 meters (243.83 feet), still 17 centimeters (6.7 inches) above the lower regulatory limit but 30 centimeters (11.8 inches) below the long-term average for this time of year. Currently, the level of the lake is about 5.7 centimeters (2.2 inches) lower than it would have been had the plan been strictly followed this year. Levels on Lake Ontario are the lowest for this time of the year since 1964. Levels on Lake St. Lawrence are at 73.11 meters (239.86 feet), 2 centimeters (0.8 inches) above average for this time of the year.
The level at the Port of Montreal on Oct. 17 was 5.48 meters (17.98 feet), 80 centimeters (31.5 inches) below average. The average September level in Montreal was a new record low, in large part because outflows from the Ottawa River have also been at record low values, due to the persistent drought conditions in the region.
The board, in conjunction with its staff, continues to monitor the drought situation carefully and is prepared to take further action as required, while also understanding that the drought conditions may persist into next summer, severely restricting what the board may be able to do. The board will continue to review conditions and revise the outflow strategy, as necessary. Outflow changes are posted to the board's Website athttp://ijc.org/conseil_board/islrbc/en/data_informations.htm and the board's Facebook site at http://www.facebook.com/ISLRBC.
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 lake residents and boating interests 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 meters (247.3 feet) and above the lower limit (from April through November) of 74.15 meters (243.3 feet) specified in the orders of approval, since regulation began in 1960, actual monthly levels have ranged from a high of 75.74 meters (248.5 feet) to a low of 73.82 meters (242.2 feet) due to climate conditions outside the plan's design range.
Levels on the St. Lawrence River fluctuate more widely. Furthermore, excessive wind setup and wave action may significantly increase local levels on both the lake and river. Strong winds can raise water levels temporarily by over half a meter (2 feet) in some locations with waves adding more water depth. Together, the temporary water level increase can exceed the monthly mean upper limit and cause shoreline damages.
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, visithttp://ijc.org/conseil_board/islrbc/en/main_accueil.htm.