Copyrights : International St. Lawrence River Board of Control

Plan 1958-D has continued to respond well in dealing with the varying supplies of recent months. The Lake Ontario level declined by a bit more than normal during November.  On December 6, the Lake level was about 1 cm (0.4 in.) below average.  Under average weather conditions, the level is expected to remain fairly stable until it starts its spring rise in March.  The long-range water levels forecast indicates the Lake would be 9 cm (3.5 in.) below average at the end of June if average weather conditions occur.

• Last month the total supplies to Lake Ontario were slightly above average.  This largely reflects the heavy rains received over the local basin as the inflow from Lake Erie was about average.   Supplies from Lake Erie are expected to remain near average for the next several months.  The 90-day weather outlooks indicate we can expect below average precipitation and temperatures.    

• Water levels in the Montreal area are expected to remain well below average for the next month if Ottawa River and local tributary inflows remain below average.

• There are still 3.7 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 hydropower or navigation in the Port of Montreal and Seaway.  The Board’s intent is to retain about this amount of water during the winter and determine whether this amount of storage is appropriate as we approach the spring.

• 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 6 months unless the most extreme wet or dry conditions occur.   The levels should also remain well below levels thought to exacerbate shoreline erosion and well above minimum levels required for safe navigation in the Seaway.
• However, there is about a 16% chance that Lake St. Louis will be so low that water intakes are impacted this winter.  The Board’s strategy allows for the release of extra water to cover this situation.
• There is about a 37% chance that the Port of Montreal will experience below-datum levels before year’s end.   This would improve if significant rainfall occurs in the next several weeks.

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.