Weekly Regulation Summary
Summary for Week Ending 20 May 2020
Lake Ontario outflows are at the maximum rate to lower water levels on Lake Ontario, while maintaining currents in the St. Lawrence River that allow for commercial navigation. For more information: https://ijc.org/en/loslrb/ijcs-international-lake-ontario-st-lawrence-river-board-announces-better-water-conditions
|Week Ending: Wed, 20 May 2020||Average this time of the year (c)|
|Lake Ontario -|
|Actual end of week level:||75.35 m (247.21 ft)||75.06 m (246.26 ft)|
|Computed Plan 2014 Level (a):||75.52 m (247.77 ft)|
|Computed Preproject Level (b):||76.19 m (249.97 ft)|
|Weekly Mean Outflow:||9820 m³/s (346800 ft³/s)||7670 m³/s (270900 ft³/s)|
|Weekly Total Supply:||9470 m³/s (334400 ft³/s)||8300 m³/s (293100 ft³/s)|
|Lake St. Lawrence at Long Sault Dam Weekly Mean Level:||72.95 m (239.34 ft)||73.67 m (241.70 ft)|
|Lake St. Louis at Pointe-Claire Weekly Mean Level:||22.07 m (72.41 ft)||21.59 m (70.83 ft)|
|Montreal Harbour at Jetty #1 Weekly Mean Level:||7.48 m (24.54 ft)||7.13 m (23.39 ft)|
|Ottawa River at Carillon Weekly Mean Outflow:||2600 m³/s (91800 ft³/s)||3000 m³/s (105900 ft³/s)|
|Preliminary Lake Ontario Outflow for Week Ending Fri, 29 May 2020:||9680 m³/s (341800 ft³/s)||7750 m³/s (273700 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.