FINAL REPORT - International Joint Commission

A key finding of the hydropower group was that the greatest benefits are realized when the range of
releases is reduced, releases are stable and predictable, and the head at Moses-Saunders Powerhouse is
higher. Releases similar to the natural cycle, with rules to limit ice jams in the winter and early spring,
come closest to achieving these conditions. It is not surprising then that Plan B + , which strives toward a
more natural regime, is the most beneficial of the three candidate plans in terms of hydropower, providing
the greatest stability and predictability, a condition favourable to hydropower planning. Nevertheless, all of
the plans create benefits for hydropower relative to 1958-DD.
FINAL REPORT
Other Interests
Interestingly, the greatest difference between plans lies in the distribution of benefits among the
recreational boating, coastal, and environmental interests. The candidate plans each result in different
trade-offs of benefits to these three interests. The following section examines more closely how the plans
perform in terms of these three interests.
Recreational Boating
From an economic perspective, Plan A + is the best plan for recreational boating. This is because Plan A + is
the most regimented of the three plans and tries to keep Lake Ontario within as narrow a range as possible
(see Figure 12). It provides slightly better boating benefits below the dam, despite lower extremes,
because most of the time summer levels remain within a narrow and favorable range.
Even though Plan B + has some negative recreational boating numbers, at public meetings, many members
of the boating community, especially on the upper river, came out in support of Plan B as it was presented
because it:
• Has better Lake St. Lawrence performance, including less frequent use of Iroquois Dam, which, when
in use, forces boaters to pass through the Iroquois Lock rather than the open dam gates;
• Generally has higher Lake Ontario levels in spring and fall (refer to Figure 27), a big plus for boat
launching and haul-out and for extending the season;
• Provides benefits over 50% of the time when compared with 1958-DD, but is worse for some Lake
Ontario and Alexandria Bay boaters during the driest years, when it keeps levels lower for longer
periods of time. However, a number of recreational boaters, especially on the upper St. Lawrence
River, expressed a willingness to trade this off for a plan that makes improvements for the
environment.
Plan D + performs similarly to 1958-DD for recreational boaters. Plan D + does allow occasional low water
levels on Lake Ontario, during low supply conditions, to benefit the environment, which creates some small
overall losses for recreational boating on the Lake. Plan D + achieves the majority of its gains for recreational
boating on the lower river primarily because, most of the time, it does not allow river levels to drop quite
as low as they do under Plan 1958-DD and it generally keeps levels higher on the lower St. Lawrence River
in the fall, extending the season and facilitating haul-out. Figure 36 shows the benefits gained by Plan D +
over the historical time sequence for recreational boaters on Lac St. Louis.
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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