Outflow Strategy
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Copyrights : International St. Lawrence River Board of Control

Lake Ontario Outflow Strategy
(May 31, 2002)

Water levels on all of the Great Lakes continued their seasonal rise in May; particularly on Lakes Erie and Ontario where they rose at a faster rate than usual. However, towards the end of May, Lake Superior and Lakes Michigan- Huron remained below average, whereas Lake Erie is close to average and Lake Ontario is 25 cm (10 in.) above average at the elevation of 75.29 m (247.01 ft). The rise in levels in the lower Great Lakes is in response to greater than average precipitation amounts in April and May.

In response to current conditions, the International St. Lawrence River Board of Control (Board) has modified the regulation strategy announced on May 23. Effective June 1, outflows will be 300 cubic metres per second (10,600 cubic feet per second) greater than called for by the regulation plan, Plan 1958-D. This overdischarge, which is subject to water levels in the Montreal area, will reduce the 6.8 cm (2.7 in.) of water currently held in reserve on Lake Ontario by about 1.0 cm (0.4 in.) per week and will continue until Lake Ontario has peaked. If Lake Ontario water levels peak in the next 3 weeks, this would leave approx. 4 cm (1.6 in.) of reserved water for critical needs of downstream navigation and power generation later this year. Downstream, Lake St. Louis water level is declining due to decreasing Ottawa River flows and is now approx. 21.5 m (70.5 ft). Presently, Montreal Harbour is about 1.25 meter (4.1 ft) above datum.

The Board is closely monitoring the conditions in the Lake Ontario-St. Lawrence system and intends to review this strategy no later than the end of June or earlier if necessary.

The International Joint commission was created under the Boundary Waters Treaty of 1909 to help prevent and resolve disputes over the use of waters along the Canada-United States boundary. Its responsibilities include approving certain projects that would change water levels on the other side of the boundary, such as the international hydropower project at Massena, New York and Cornwall, Ontario. When it approves a project, the Commissionís Orders of Approval may require that flows through the project meet certain conditions to protect interests in both countries. For more information, visit the Commissionís website at www.ijc.org.

The International St. Lawrence River Board of Control was established by the International Joint Commission, mainly to ensure that outflows from Lake Ontario meet the requirements of the Commissionís Orders of Approval. For more information, visit the Boardís website at www.islrbc.org.

For Release: May 31, 2002


Reg Golding, Ottawa, Ontario (613) 998-1408

John Kangas, Chicago, Illinois (312) 353-4333