FINAL REPORT - International Joint Commission

FINAL REPORT
Beyond the Summary Numbers
+ + +
Figure 35: Environmental benefit ratios by sector based on historical analysis
All of the candidate plans create overall economic and environmental benefits relative to 1958-DD, but to
varying degrees. The Study Board is confident that any one of these plans would provide an overall
improvement over the existing plan. In selecting these candidate plans, the Study Board viewed and
assessed the plan data in numerous ways and in varying detail. All of the plan results were available to the
Study Board through the Board Room. There is far too much information within the Board Room to be
covered in this report. The purpose of this section is to identify the critical issues and nuances and
highlight the key pros and cons of each of the plans to allow a more informed decision.
Commercial Navigation, Hydropower and Municipal, Industrial and Domestic Water Uses
From an interest perspective, all three candidate plans benefit commercial navigation and hydropower and
have no measurable impact on municipal, industrial or domestic water uses. If we examine the results of
the plans for these three interest categories in detail, we find the following:
None of the plans harm municipal, industrial and domestic water uses compared with Plan 1958-DD.
This is because water-use facilities are generally not vulnerable to water level changes except under
extremely low water supply conditions, which would occur more frequently under the climate change
scenarios. Under these conditions, all of the plans would have unavoidable impacts at Montreal, but this
risk is being addressed by city managers. As noted earlier, the County of Monroe potable water pumping
and treatment plant on the south shore of Lake Ontario reports flood damages at high lake levels, but did
not quantify the damages associated with this situation. Two power stations, Ginna and Russel, also on
the south shore of Lake Ontario would experience problems within the historical record, and will require
upgrading to remain fully operational under future high and low water level conditions under any plan,
including the existing one.
All of the plans help commercial navigation overall. The main difference between plans is the costs
induced by delays to shipping on the Seaway. There is almost always enough water on Lake Ontario to
keep ships fully loaded, and none of the plans can eliminate shallow depths in the Seaway and Port of
Montreal. However, Plan D + is preferred by navigation representatives for its Montreal performance, where
it tends to even out seasonal levels in dry years; Plans A + and B + provide higher levels in the spring (which
bring little or no benefit to shippers) and then must drop levels below chart datum in the fall of drier years,
while Plan D + can often maintain chart datum. These differences are not significant, on average, because
all the plans have essentially the same average annual shipping costs in Montreal. But the slightly greater
reliability of adequate depths under Plan D + makes it more desirable for the Port of Montreal.
62 Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows