The International St. Lawrence River Board of Control (Board) reviewed conditions in the Lake Ontario - St. Lawrence River system on October 13 and decided to continue with the same outflow strategy that has been in effect since September 21, that is, the release of outflows specified by Plan 1958-D. In addition, the Board decided to permit over-discharges to meet critical needs of hydropower and downstream navigation interests that may arise as well as to maintain levels at Pointe-Claire on Lake St. Louis above 20.6 m (67.6 ft.). Any such over-discharge will be limited to no more than 600 cubic metres per second (cms) (21, 200 cubic feet per second (cfs)) per day and 300 cms (10, 600 cfs) per week. The rationale for this strategy is as follows:

• Plan 1958-D has continued to respond well in dealing with the increased supplies left by the remnants of Hurricane Frances. The higher outflows specified by the Plan have helped reduce the level on Lake Ontario more rapidly than its normal rate of decline at this time of year. On October 13, the Lake level was 8 cm (3 in.) above average. The level is expected to decline to the long-term average by late October if conditions remain dry or mid November if normal amounts of precipitation and evaporation occur on the basin in the coming weeks and Plan 1958-D outflows continue to be followed.
• The total supplies to the Lake have been below average for most of the period since the September meeting. This is largely because there was not much rainfall over the local basin. Supplies from Lake Erie have been near the average and are expected to remain there for the next few months. Precipitation on the Lake Ontario basin and evaporation from the Lake surface will be the key factors in establishing Plan outflows and the rate of decline in the Lake level over the next few weeks.
• The Board will closely monitor precipitation amounts, Plan outflows and the rate of decline in the Lake over the coming days and weeks. The Board will take action to avoid too large a drop in water levels in the Montreal area if there is a large reduction in the Plan outflow, especially if conditions remain dry.
• Water levels in the Port of Montreal area are currently below average, largely as a result of below average inflows from the Ottawa River and local tributaries. The levels are expected to remain well below average for the next month if Ottawa River and local tributary inflows remain below average.
• Lake St. Louis levels are currently slightly above average but are expected to drop below average and by month’s end if conditions remain dry.
• There are still 4 cm (1.5 in.) of water conserved on Lake Ontario, being held to meet critical needs of interests. There is a chance that a portion of this reserve might be needed to assist navigation in the Port of Montreal and Seaway in November and December if conditions are dry over the next several weeks.
• The results of the September risk analysis remain valid and show that the level of Lake Ontario will remain well within the range of levels specified in the International Joint Commission’s criteria for regulation of Lake Ontario for the next 8 months unless the most extreme wet or dry conditions occur. However, there is still a significant chance that levels in the Montreal area will drop below chart datum by the end of December, if conditions remain dry.

The Board, in conjunction with its staff, will continue to monitor the situation, and will meet again in about four weeks to re-assess the situation, or earlier if there is a significant change in conditions before then.

This information can also be found on the Board’s web site (see address below), where it is updated as required.

For Release: October 15, 2004