The International St. Lawrence River Board of Control (Board) reviewed conditions in the Lake Ontario - St. Lawrence River system on March 9 and decided to modify the regulation strategy that had been in place since last fall. That strategy was to closely follow the outflows prescribed by regulation Plan 1958-D, while allowing for critical needs to be met. The water conserved on Lake Ontario (relative to Plan-prescribed outflows) since last summer to meet the needs of interests was almost entirely preserved, with 2.8 cm (1.1 in) remaining. In view of the current and expected conditions of Lake Ontario and the St. Lawrence River, the Board strategy is to eliminate the conserved water, as conditions allow. Flows higher than those specified by Plan 1958-D will be released if doing so does not cause undue harm to interests. For example, levels downstream will be maintained below the flood alert level, the capacity of the hydropower facilities to discharge flows without spilling through open channels, and ice conditions may each limit the ability to discharge more than the outflows specified by the regulation plan. In looking to the summer, the Board noted that there is little risk of exceeding either the upper or lower water level limits.

Other factors considered in deciding on this strategy are as follows:

• Plan 1958-D has continued to respond well in dealing with the above-average water supplies of recent months. The Lake Ontario level has risen more than normal since the beginning of January. On March 9^th, the Lake level was at 74.86 m (245.60 ft). This level is 22 cm (8.7 in.) above average. Under average weather conditions, the level is likely to rise slowly. The long-range water levels forecast indicates the Lake would be 1 cm (0.4 in.) below average at the end of June if average weather conditions occur and all of the conserved water is removed.
• Last month the total supplies to Lake Ontario were well above average. This largely reflects the heavy precipitation received over the local basin as well as above-average inflow from Lake Erie. Supplies from Lake Erie are expected to remain above average for the next several months.
• Water levels in the Montreal area are expected to remain below average, but above Chart Datum, over the next six months.
• Risk analysis shows 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 ten months unless extreme wet or dry conditions occur.
• However, there is about a 25% chance that Lake St. Louis will reach the flood level of 22.33 m this spring. The Board’s strategy allows for the release of flows less than specified by the regulation plan to mitigate this situation. There is also a 30% chance that levels in Lake St. Louis will be below the minimum required for Seaway navigation at some point late in 2005.
• There is about a 59% chance that the Port of Montreal will experience below-datum levels at some point late in 2005.

The Board, in conjunction with its staff, will continue to monitor the situation, and will meet again in about four weeks to reassess 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.

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 Commission’s Orders of Approval may require that flows through the project meet certain conditions to protect interests in both countries. For more information, visit the Commission’s 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 Commission’s Orders of Approval. For more information, visit the Board’s website at www.islrbc.org.

Contacts:

Reg Golding, Ottawa, Ontario (613) 998-1408 e-mail: GoldingR@dfo-mpo.gc.ca

John Kangas, Chicago, Illinois (312) 353-4333 e-mail: John.W.Kangas@usace.army.mil