Weekly Regulation Summary

Summary for Week Ending 22 January 2020

Colder temperatures allowed ice formation to resume in the Beauharnois Canal last week, and outflows have been adjusted to facilitate a safe and stable ice cover. Outflows will continue to be adjusted as necessary, according to conditions in the St. Lawrence River.

  Week Ending: Wed, 22 Jan 2020 Average this time of the year (c) 
Lake Ontario -    
         Actual end of week level: 75.08 m  (246.33 ft) 74.59 m  (244.72 ft)
         Computed Plan 2014 Level (a): 75.21 m  (246.75 ft)  
         Computed Preproject Level (b): 75.92 m  (249.08 ft)  
         Weekly Mean Outflow: 7960 m³/s  (281100 ft³/s) 6400 m³/s  (226000 ft³/s)
         Weekly Total Supply: 9350 m³/s  (330200 ft³/s) 6980 m³/s  (246500 ft³/s)
Lake St. Lawrence at Long Sault Dam Weekly Mean Level:  73.17 m  (240.06 ft) 72.95 m  (239.34 ft)
Lake St. Louis at Pointe-Claire Weekly Mean Level:  21.71 m  (71.23 ft) 21.31 m  (69.91 ft)
Montreal Harbour at Jetty #1 Weekly Mean Level:  7.20 m  (23.62 ft) 6.75 m  (22.15 ft)
Ottawa River at Carillon Weekly Mean Outflow: 2350 m³/s  (83000 ft³/s) 1940 m³/s  (68500 ft³/s)
Preliminary Lake Ontario Outflow for Week Ending Fri, 31 Jan 2020: 8700 m³/s  (307200 ft³/s) 6530 m³/s  (230600 ft³/s)

Levels are in metres (feet) IGLD 1985.  Supply and flows are in cubic metres (feet) per second m³/s (ft³/s).  

(a) Levels that would have occurred with strict adherence to Plan 2014.

(b) Levels that would have occurred had there been no Lake Ontario regulation.        
(c) For comparison purposes, Lake Ontario water level data since 1918 are used to be consistent with those published in the  US and Canadian Great Lakes bulletins (https://www.waterlevels.gc.ca/C&A/bulletin-eng.html). Other averages are for the periods as follows: Lake Ontario outflows and levels at Long Sault and Pointe-Claire since 1960; Montreal since 1967; and Ottawa River outflow at Carillon since 1963.        
The regulation plan for Lake Ontario specifies a weekly average outflow from Saturday through the following Friday, inclusive.  To provide timely information for the coming week to the hydropower and Seaway operators, and our readers, we complete the regulation plan calculations each Thursday.  Our calculations use the data available at the time, which are from the previous seven days (Thursday through Wednesday). Since the two time periods do not exactly coincide, their data are usually slightly different.          
The table shows the actual flow for the week ending Wednesday.  It also gives the preliminary flow for the coming week ending Friday.  We emphasize that this is the preliminary flow, since unforeseen flow changes may occur after we have issued our notice.  When these flow changes occur, they are reflected in the subsequent week's notice.

Information in this report is compiled from provisional data provided by: Environment & Climate Change Canada, Fisheries and Oceans Canada, Hydro Quebec, Ontario Power Generation Inc, the New York Power Authority, and the U.S. National Ocean and Atmospheric Administration.