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IJC board announces Lake Ontario water level adjustments for winter

by jmaloni


Sat, Dec 28th 2013 07:00 am

The International Joint Commission, which regulates levels in the Lake Ontario-St. Lawrence River system has announced water level adjustments for the winter season.

The IJC's International St. Lawrence River Board of Control recently reviewed conditions in the Lake Ontario-St. Lawrence River system and noted a rapid onset of winter. With the arrival of cold temperatures has comes the formation of ice in the St. Lawrence River. As a result the board has directed changes in the lake levels to influence levels downstream in the river system.

The board plays an active role in ensuring the formation of a stable ice cover. This is essential to minimize the risk of ice-related issues, such as flooding and to ensure that water levels and flows can continue to be managed in accordance with the IJC's Orders of Approval for the regulation of Lake Ontario. Therefore, the board will typically reduce outflows as the ice formation begins.

Reduced outflows result in reduced water velocity; this aids in forming a solid ice cover that can withstand flow increases later. The reduced flows for ice formation may result in some temporary storing of water compared to strictly following the IJC regulation plan. The water stored during ice formation is typically offset by increased outflows when the ice cover is sufficiently stable.

The board expects that the water stored in early 2014 will be removed soon as outflows transition to the flows required for ice formation. The board will continue to permit additional under- or over-discharges that may be necessary to address unforeseen critical conditions in the river.

After starting the year well below average, and peaking in July above average, Lake Ontario is currently nearing its normal seasonal low. The level on Dec. 19 was 74.49 meters (244.39 feet), about 4 centimeters (1.6 inches) below long-term average for this time of year. This is well within Lake Ontario's 1.22 meters (4 foot) range, being 88 centimeters (34.6 inches) below the lake's upper limit, and 34 centimeters (13.4 inches) above its lower limit.

Lake St. Lawrence, just upstream of the Moses-Saunders powerhouse, was about 30 centimeters (11.8 inches) above average. Downstream, the levels at Pte. Claire on Lake St. Louis were 23 centimeters (9.1 inches) below average, 38 centimeters (15.0 inches) above the Seaway Alert level; and at Montreal Harbor, levels were 21 centimeters (8.3 inches) below average, but 74 centimeters (29.1 inches) above chart datum.

The board, in conjunction with its staff, continues to monitor the situation closely and is prepared to take further action as required. 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 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. Residents and boating interests are urged 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) as 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. 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 more than half a meter (2 feet) in some locations.

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 http://ijc.org/en_/islrbc. To receive a weekly email about water levels and flows in the Lake Ontario-St. Lawrence River system, send a blank email message to [email protected] with the word "subscribe" in the title and body of your message.

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