FINAL REPORT - International Joint Commission

Overall Plan Results
All of the candidate plans create overall economic and environmental benefits compared with 1958-DD, but
differ in their distribution of these benefits. Table 4 below provides a summary of overall results. A further
breakdown and discussion of these results will follow. The total net benefits are a summation of all economic
performance indicators (positive and negative). The total of losses provides an indication of disproportionate
loss by showing a sum of all losses caused by a plan. The overall environmental index provides an
indication of the environmental benefits of each of the plans, shown as a ratio. This is further supported
by the meadow marsh wetlands score, which is an important indicator discussed later in the report. Also
shown are the number of environmental performance indicators that show more than a 10% improvement
relative to Plan 1958-DD or greater than a 10% deterioration relative to 1958-DD. Finally, this table also
shows the number of species at risk impacted by a given plan by more than a 10% difference relative to
1958-DD. Plan E evaluations are presented for comparison purposes only, as Plan E is not a candidate
plan for consideration.
FINAL REPORT
Table 4: Summary Results (economic results determined from stochastic, environmental ratios
based on historical supply sequence)
Impact 1 Plan A + Plan B + Plan D + Plan E
Total Net Benefits 2 $6.44 $4.63 $4.48 -$16.36
Total of Losses (all sectors) 3 -$0.90 -$4.35 -$0.73 -$33.87
Overall Environmental Index 4 1.06 1.35 1.10 4.04
Meadow Marsh Index 5 1.02 1.44 1.17 1.56
Environmental PIs better off 6 3 7 5 9
Environmental PIs worse off 7 5 3 1 3
Species at Risk better off 8 0 2 0 3
Species at Risk worse off 9 1 0 0 0
Notes to Table 4:
1. All impacts are measured relative to the estimated impact of Plan 1958-DD.
2. Economic figures represent the average annual impact relative to Plan 1958-DD; figures are reported in millions of
U.S. dollars and are based on the 50,000-year stochastic supply series, using a 4% discount rate over a 30-year
period, for coastal erosion and shore protection maintenance.
3. Total of Losses (all sectors) is the sum of all negative economic benefits for a plan.
4. The Overall Environmental Index was developed by Limno-tech for the Study Board. The Index is described in
Annex 1 of this report. Scores are presented as ratios, with 1 representing no change from Plan 1958-DD, less
than 1 a deterioration relative to 1958-DD, and greater than 1 an improvement relative to 1958-DD. Results are
based on the historical sequence.
5. The Wetland Meadow Marsh Community performance indicator has been highlighted as a priority performance
indicator for environmental health on Lake Ontario. It is presented as a ratio (see 4 above).
6. This measure indicates the number of environmental performance indicators that score significantly (>10%) higher
than 1.0, indicating that the given plan performs better than Plan 1958-DD.
7. This measure indicates the number of environmental performance indicators that score significantly (>10%) less
than 1.0, indicating that the given plan does not perform as well as Plan 1958-DD.
8. This measure indicates the number of Species-at-Risk performance indicators that score significantly (>10%)
higher than 1.0, indicating that the given plan performs better than Plan 1958-DD.
9. This measure indicates the number of Species-at-Risk performance indicators which score significantly (>10%)
lower than 1.0, indicating that the given plan does not perform as well as Plan 1958-DD.
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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