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

Lake Ontario Outflow Strategy
(July 11, 2003)

Water levels on all of the Great Lakes, with the exception of Lake Superior, rose in June, but they all remain lower than they were a year ago. Lake Ontario apparently peaked in June at a level of 75.13 m (246.49 ft.). So far in July, it has fallen about 3 cm (1.2 in.). As of July 8, its level of 75.06 m (246.26 ft.) was still 2 cm (0.8 in.) above its average for this time of year. Lake St-Louis and Montreal Harbour levels improved in June and July and remain well above datum. Since June 7, there is approximately 4.3 cm (1.7 in.) of water conserved on Lake Ontario.

Forecasts indicate that the lake should remain above average until at least November under average precipitation conditions. However, precipitation over the Lake Ontario basin has been

erratic lately. The monthly mean basin precipitation estimates for April, May and June are 70%, 160% and 89% of their long-term averages, respectively.

The Board reviewed these and other conditions and agreed to maintain the strategy as announced on June 23. The long-term strategy, in consideration of the continued below average levels on the upper Great Lakes, is to have enough water to meet critical needs later in the year within current system constraints. The short-term strategy, in consideration of Lake Ontarioís current water level and the recent erratic weather patterns throughout the basin, is to retain as much of the water conserved on Lake Ontario as possible.

Through the second week of August, outflows will generally be as determined by Regulation Plan 1958-D except for the following deviations:

a) Flow increases to maintain Lake St. Louis levels above 20.6 m (67.6 ft.) and the level of Lake St. Francis at Summerstown above 46.58 m (152.82 ft.)

b) Flow increases to meet critical hydropower needs and to raise levels at the Port of Montreal for critical navigation needs at a maximum weekly over-discharge of 300 m3/s (10,600 cfs) and no more than a maximum daily over-discharge of 600 m3/s/day ( 21,200 cfs/day) above Plan flow. A flow change of 300 m3/s will result in a change in level at Montreal of about 10 cm (3.9 inches) and, after a week, a change in Lake Ontario level of about 1 cm (0.4 inch.).

Additional water may be stored if warranted. Currently, the Board does not foresee opportunities for additional storage before mid-August.

The Board intends to review this strategy in mid-August at its regularly scheduled monthly teleconference. The Board, in conjunction with its staff, continually monitors the conditions on the Lake Ontario-St.Lawrence River System.

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: July 11, 2003


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

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