The International St. Lawrence River Board of Control (Board) reviewed conditions in the Lake Ontario - St. Lawrence River system on May 9 and decided to closely follow the outflows prescribed by regulation Plan 1958-D for the next month.  The Board reaffirmed this decision on May 12, after considering the comments received at its meeting with the public the evening of May 11 in Belleville, Ontario.  The Board took note of the conditions since it last met in April.  Precipitation in April was estimated at about 11.3 cm (4.4 in), well above average.  Due to the rainfall, and the flow reductions required to prevent flooding downstream, Lake Ontario rose about 31 cm (12.2 in) in April.  The average water levels rise is April is 21 cm (8.3 in).  Plan 1958-D continues to respond to the above average Lake Ontario levels by specifying increased outflows.  These outflows are the highest since 1998 for this time of year.  There is still a risk of flooding downstream over the next several weeks. Considering this risk of downstream flooding, the current high outflows, and the impacts on other interests of flows greater than specified by Plan 1958-D, the Board decided to closely follow Plan 1958-D and retain the water conserved on Lake Ontario until its next meeting.

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

·         Plan 1958-D continues 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 May 10^th, the Lake level was at 75.14 m (246.52 ft).  This level is 14 cm (5.5 in) above average.  Under average weather conditions, the level is expected to slowly fall through early summer.  

·        Last month the total supplies to Lake Ontario were well above average.  Both the inflow from Lake Erie and the inflow from the local drainage basin were well above average.  

• 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 eight months unless extreme wet or dry conditions occur.  The risk of Lake Ontario exceeding the upper limit during 2005 is now estimated at 3%; last month the risk was estimated at 2%.  
• Lake St. Louis level varied between 30 cm (12 in) below and a few cm above its flood alert level of 22.1 m (72.5 ft) during the past month.  This necessitated several outflow reductions when the water level at Pointe Claire exceeded the alert level.  However, the levels of the past week have seen a steady decline.  Lake Ontario outflows will be reduced again if needed to avoid flooding. 
• Water levels in the Montreal area have risen significantly over the past month and are expected to remain above average through most of June, and above Chart Datum through the end of October.  There is about a 55% chance that the Port of Montreal will experience below-datum levels at some point later in 2005.  Last month the risk was 60%. 

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.

For Release: May 17, 2005

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