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St. Lawrence River Board of Control says water to stay at prescribed levels

Posted 11/4/14

The International St. Lawrence River Board of Control says after a review of water levels in the Lake Ontario-St. Lawrence River system, they will keep them as prescribed in Plan 1958-D. "The …

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St. Lawrence River Board of Control says water to stay at prescribed levels

Posted

The International St. Lawrence River Board of Control says after a review of water levels in the Lake Ontario-St. Lawrence River system, they will keep them as prescribed in Plan 1958-D.

"The regulation plan specifies the Lake Ontario outflow based on the level of the lake, the time of year and certain limitations to protect interests in the St. Lawrence River," board spokesperson Sarah Lobrichon replied via email when asked to describe the specifics of the plan.

Water levels throughout the system are all close to their long-term averages, and well within the limits of the regulation plan, the board says. They say they will continue to permit additional under- or over-discharges that may be necessary to address critical conditions, though none are foreseen at this time.

Lake Ontario is slightly below its long-term average level for this time of year. The level on October 22 was 74.57 meters (244.65 feet) above sea level, 2 centimeters (0.8 inches) below average. This is well within Lake Ontario’s 1.22 meter (4 foot) range, being 80 centimeters (31.5 inches) below the lake’s upper limit, and 42 centimeters (16.5 inches) above the lake’s lower limit. The level at Lake St. Lawrence, just upstream of the Moses-Saunders powerhouse, was about 42 centimeters (16.5 inches) below average. Downstream, the level at Lake St. Louis was 25 centimeters (9.8 inches) above average. At Montreal Harbour, the level was 32 centimeters (12.6 inches) above average, the board said.

Outflow changes are posted to the board’s Facebook site at www.facebook.com/ISLRBC (English) and its website at http://ijc.org/en_/islrbc under the "Maps and Data" tab, 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.

Although the board says they strive 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 75.73 meters (248.5 feet) to a low of 73.82 meters (242.2 feet) due to climate conditions outside the design range.

Levels on the river tend to vary more widely. 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 (two feet) in some locations, the board said in a prepared statement.