FINAL REPORT - International Joint Commission

This procedure is repeated until the trial flow equals 6,880 (6,480 + 400) m3/s (243,000 ft3/s). The plan
then checks which trial flow (from 6,080 to 6,880 m3/s or roughly 214,700 to 243,000 ft3/s) results in the
highest total score. The trial flow with the highest score is 6,410 m3/s (226,400 ft3/s) with a total score of
1,050.83. The forecast Lake Ontario level with this score is 74.40 m (244.09 ft). The individual scores for
a flow of 6,410 m3/s (226,400 ft3/s) in this case are:
ANNEX 3
Lake Ontario Score for Deviation from Target Level: 31.86
Lake Ontario Score added in Recreational Boating Season: 5.46
Seaway Navigation Score: 2.73
Flow Score for River Upstream of Moses-Saunders Dam: 1.00
Flow Change Score: 0.00
Lac St. Louis at Pointe Claire Level Score: 7.00
Lake St Lawrence Level Score: 1,000.00
Lake Ontario Flow Score for Conditions on the Beauharnois Canal: 0.59
St. Lawrence River at Montreal Score: 2.19
Lac St. Louis at Pointe Claire Level Score Add Boating Season: 0.00
For the second quarter-month of 1947, the Lake Ontario flow is 6,410 m3/s (226,400 ft3/s).
Under certain conditions, such as the transition from open water to ice formation conditions, the lowest
trial flow is permitted to be as much as 6,000 m3/s (212,000 ft 3 /s) lower than the previous quarter-month
flow (rather than only 400 m3/s (14,100 ft 3 /s) lower) to allow the flow to be reduced for ice formation. If the
levels in the lower river are high (above 22.0 m (72.18 ft) at Pointe Claire), the highest trial flow can be as
much as 1,500 m3/s (53,000 ft 3 /s) higher than the previous quarter-month flow (rather than only 400 m 3 /s
or 14,100 ft3/s higher) to allow the flow to rebound after being reduced for the Ottawa River freshet.
The following example explains this situation.
Example 2: Calculating the flow for quarter-month 19 of 1947.
The Lake Ontario outflow in the 18th quarter-month of 1947 is 7,080 m3/s (250,000 ft 3 /s) and the level at
end of the 18th quarter-month is 75.27 m (246.95 ft). The forecast net total supply (NTS) for quartermonth
19 is 8,533 m3/s (301,300 ft 3 /s) and open water conditions exist in the Beauharnois Canal and
upstream of the Moses-Saunders Dam. The Lac St. Louis level at quarter-month 18 is 22.06 m (72.38 ft).
The Lake Ontario target level for quarter-month 19 is 75.05 m (246.23 ft).
Since the previous Lac St. Louis level was over 22 meters (72.18 ft), for quarter-month 19 the plan
determines the initial trial flow to be 5,000 m3/s (176,600 ft 3 /s). This is the maximum of the previous flow
minus 3,500 m3/s (7,080 - 3,500 = 3,580 m 3 /s or 126,400 ft 3 /s) and the minimum flow constraint for
quarter-month 19, which is 5,000 m3/s (176,600 ft 3 /s), as shown in Figure B-29. The high end of the trial
flow range is determined to be 8,580 (= 7,080 + 1,500) m3/s (303,000 ft 3 /s).
The scores for the trial flows from 5,000 m3/s to 8,580 m 3 /s (176,600 to 303,000 ft 3 /s) in increments of
10 m3/s (350 ft 3 /s) for quarter-month 19 are determined. The highest total score occurs for the trial flow of
7,660 m3/s (270,500 ft 3 /s). The total score for this flow is 1,033.32, with the individual scores shown below.
Lake Ontario Score for Deviation from Target Level: 20.30
Lake Ontario Score added in Recreational Boating Season: 4.01
Seaway Navigation Score: 3.00
Flow Score for River Upstream of Moses-Saunders Dam: 1.03
Flow Change Score: 0.00
Lac St. Louis at Pointe Claire Level Score: 2.80
Lake St Lawrence Level Score: 1,000.00
Lake Ontario Flow Score for Conditions on the Beauharnois Canal: 0.80
St. Lawrence River at Montreal Score: 1.11
Lac St. Louis at Pointe Claire Level Score Add Boating Season: 0.27
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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