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

Lake Ontario Outflow Strategy
(March 27, 2002)

While water levels on the upper Great Lakes (Lake Superior and Lakes Michigan-Huron) remain below average, all of the Great Lakes are higher than one year ago. Lakes Ontario, Erie and Michigan-Huron are 15 cm (6 in.), 13 cm (5 in.), and 22 cm (9 in.), respectively, higher than one year ago. Lake Erie is at its long-term average and Lake Ontario is 12 cm (5 inches) above long-term average. Precipitation amounts on the Great Lakes basins in February were above average, except for Lake Ontario basin which received about one-quarter less than usual..

The water levels at most locations in the Thousand Islands area of the St. Lawrence River are above average by an amount similar to that for Lake Ontario. Downstream, the Lake St. Louis and Montreal Harbour levels are about 8 cm and 62 cm (3 in and 24 in.) respectively, lower than average. Montreal Harbour levels in recent days have been between 80 cm and 90 cm (31 to 35 inches) above chart datum. Flows from the Ottawa River into the Montreal region of the St. Lawrence River are currently slightly above average.

At present, the amount of water retained on Lake Ontario is 7.9 cm (3.1 inches), a net result of all previous under-discharges and over-discharges relative to the Regulation Plan 1958-D.

With the level of Lake Erie near its long-term average, the supply of water to Lake Ontario from that lake is expected to remain near average during the coming months. If weather conditions on Lake Ontario basin are near average for the next few months, its levels should continue to rise and peak this coming June about 8 cm ( 3.1 in.) above its average of 75.04 m (246.2 ft.).

At a meeting on March 19-20, 2002, the Board considered these and other relevant conditions and decided on the following regulation outflow strategy:

Generally, outflows specified by Plan 1958-D will be followed, except for flow reductions (if needed) to prevent flooding in the Montreal region during the Ottawa River freshet. Lake St. Loius will be kept below its flood alert level of 22.1 m (72.5 feet). Any flow decreases for the freshet will be offset as soon as opportunities arise. The Boardís intent is to retain 7.9 cm (3.1 in.) of conserved water to meet critical navigation and hydropower needs later this year.

The Board intends to review this strategy in April, or before if conditions require.

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: March 27, 2002


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

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