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

Lake Ontario Outflow Strategy
(April 15, 2002)

Water levels on all of the Great Lakes, except Lake Ontario, remain below average, but all of the lakes are higher than one year ago. Lakes Ontario and Erie are 13 cm (5 in.) higher than one year ago, while Lakes Michigan-Huron are 21 cm (8.3 in) higher. Lakes Erie and Michigan-Huron are 5 cm (2 in.) and 39 cm (15 in.), respectively, below long-term average while Lake Ontario is 6 cm (2.4 in.) above its long-term average. Precipitation amounts on all of the Great Lakes basins in March were above average.

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 48 cm and 95 cm (19 in. and 37 in.) respectively, lower than average. Montreal Harbour is about one metre (3 ft.) above chart datum. Since March 31, flows from the Ottawa River into the Montreal region of the St. Lawrence River are slowly increasing due to snowmelt on the lower Ottawa River basin. However, no reductions in the Lake Ontario outflow has been necessary to date as water levels in the Montreal region remain below flood stage.

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 outflows specified by Regulation Plan 1958-D.

With the level of Lake Erie slightly below its long-term average, the supply of water to Lake Ontario from that lake is expected to remain near to slightly below average during the coming months. If weather conditions are near average for the next few months, Lake Ontarioís level should continue to rise and peak this June about 6 cm ( 2.4 in.) above its average of 75.04 m (246.2 ft.). Levels in the Montreal region are expected to peak later this month, or in May, about 0.6 metre (2 ft.) below average; with summer and fall levels below average and similar to last year.

At a meeting on April 9, 2002, the Board considered these and other relevant conditions and decided to continue the regulation outflow strategy announced 3 weeks ago:

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 spring runoff. Lake St. Louis will be kept below its flood alert level of 22.1 m (72.5 feet). Any such flow decrease 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 July, 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: April 15, 2002


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

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