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The following graphs represent the likely range of water levels for Plan 1958DD, the three candidate plans, and Plan E (a reference plan) based on the 50,000-year stochastic supply sequence for four locations: Lake Ontario, the upper St. Lawrence River at Long Sault, and the lower St. Lawrence River at Lac St. Louis and Montreal Harbour. The graphs include levels that we expect to be fairly common and levels we think could happen but are not likely to be seen in any one lifetime. The measure of probability is the expected number of years between occurences of that level - 100 year return levels are less likely than 20 year levels. The highest and lowest levels shown on each graph have recurrence intervals of thousands of years. We include these rare and extreme levels to test how well a plan would respond to them. This is important because even though these events are unlikely, the impacts could be enormous. It is not unusual for release rules to work well when water levels are closer to average, but perform badly in wetter or dried conditions. To view a graph, select a location and a plan from the two drop down menus and click "View Graph Now!".
