Lake Ontario Outflow Changes
The regulation plan (Plan 2014) specifies a weekly average Lake Ontario outflow from Saturday through the following Friday. Throughout the year, the Lake Ontario outflow, which is managed at the Moses-Saunders Dam, may be modified more frequently depending on the conditions in Lake Ontario and the St. Lawrence River. There are two different types of outflow modifications:
- Operational Adjustments, which do not have to be offset at a later date, and
- Deviations, which are classified as "minor" or "major" and generally do have to be offset at a later date.
Further details are available in the Directive on Operational Adjustments, Deviations and Extreme Conditions (https://ijc.org/en/loslrb/who/directives/deviations)
Summary of Outflow Changes in 2022
Summary of Outflow Changes for 2023
As of January 7, 2023, the water level of Lake Ontario was equivalent to the level it would have been if no outflow deviations from Plan 2014 had been conducted in 2022.
January 27, 2023:
The Lake Ontario outflow has been reduced to promote the formation of an ice cover in the Beauharnois Canal. This outflow reduction is considered an operational adjustment in accordance with the Plan 2014 I Limit. About 2 km of slush ice has accumulated in the Beauharnois Canal and there has been a significant rise in the tension on the ice booms.
February 2, 2023:
Ice began to form in the Beauharnois Canal on January 27. Since then, the outflow has been operationally adjusted several times (decreased on January 27, increased on January 29 and 30, decreased on January 31, and increased on February 1) in accordance with the Plan 2014 I Limit and in response to changing ice conditions.
The outflow target for the week of February 4 through 10 is the applicable Rule Curve flow of 7,720 m3/s. However, the outflow will continue to be operationally adjusted in accordance with the Plan 2014 I Limit, as needed, to promote the formation and stability of an ice cover in the Beauharnois Canal.
Winter Outflow Changes
During the winter months, the outflow will be operationally adjusted in accordance with the Plan 2014 I Limit, as needed, to promote the formation and stability of ice covers in the Beauharnois Canal and on Lake St. Lawrence. For more information,
- This video demonstrates the importance of ice management in the St. Lawrence River: https://vimeo.com/168823489
- FAQ 2.7 “What actions does the Board take to manage ice conditions in the St. Lawrence River during the winter?” : https://ijc.org/en/loslrb/watershed/faq/2#2-7
- FAQ 4.8.4 “What is the I Limit?”: https://ijc.org/en/loslrb/watershed/faq/4#4-8-4
- This video discusses winter operations under Plan 2014: https://vimeo.com/670845537
DATE | HOUR | OUTFLOW | OUTFLOW | NOTES |
(YYYY-MM-DD) | (HHMM) | (m3/s) | (cfs) | |
2023-02-02 | 1701 | 6,800 | 240,100 | I Limit |
2023-02-01 | 1901 | 7,700 | 271,900 | Rule Curve |
2023-01-31 | 2001 | 7,000 | 247,200 | I Limit |
2023-01-30 | 1301 | 7,700 | 271,900 | Rule Curve |
2023-01-29 | 1201 | 7,500 | 264,900 | I Limit |
2023-01-27 | 1401 | 7,000 | 247,200 | I Limit |
2023-01-21 | 0001 | 7,620 | 269,100 | Rule Curve |
2023-01-14 | 0001 | 7,600 | 268,400 | Rule Curve |
2023-01-07 | 0001 | 7,490 | 264,500 | Rule Curve |
To view outflow change records from previous years, please use the links below: