FINAL REPORT - International Joint Commission

ANNEX 3
Examples
Example 1: Calculating the flow for the second quarter-month of 1947.
The Lake Ontario outflow in the first quarter-month of 1947 is 6,480 m3/s (228,800 ft 3 /s) and the level
at end of the first quarter-month is 74.39 m (244.06 ft). The forecast net total supply (NTS) for the
second quarter-month is 6,824 m3/s (241,000 ft 3 /s), and the ice cover is considered to be formed in the
Beauharnois Canal and upstream of the Moses-Saunders Dam. The Lake Ontario target level for quartermonth
two is 74.48 m (244.36 ft).
For the second quarter-month, the lowest trial flow is 6,080 (= 6480 - 400) m3/s (214,700 ft 3 /s). For this
trial Lake Ontario flow of 6,080 m3/s (214,700 ft 3 /s), the beginning-of-quarter-month Lake Ontario level of
74.39 m (244.06 ft), forecast NTS of 6,824 m3/s (241,000 ft 3 /s), the program calculates the trial Lake
Ontario end-of-quarter-month level for qm two (74.39 + (6,824 - 6,080)/29,700 = 74.42 m)(244.16 ft), the
downstream water levels using forecast tributary flows and roughness, and each benefit score. For the
first trial flow of 6,080 m3/s (214,700 ft 3 /s), the individual benefit scores are as follows:
Lake Ontario Score for Deviation from Target Level: 32.98
Lake Ontario Score added in Recreational Boating Season: 5.65
Seaway Navigation Score: 2.83
Flow Score for River Upstream of Moses-Saunders Dam: 0.40
Flow Change Score: 0.00
Lac St. Louis at Pointe Claire Level Score: 6.22
Lake St Lawrence Level Score: 1,000.00
Lake Ontario Flow Score for Conditions on the Beauharnois Canal: 0.37
St. Lawrence River at Montreal Score: 0.90
Lac St. Louis at Pointe Claire Level Score Add Boating Season: 0.00
The total score for this trial flow of 6,080 m3/s (214,700 ft 3 /s) is the sum of individual scores, or 1,049.35.
Plan D + then checks to see whether the trial flow is greater than high end of the trial flow range, which in
this case is 6,880 (= 6.480 + 400) m3/s (243,000 ft 3 /s). If it is not, the flow is incremented by 10 m 3 /s
(350 ft3/s), which makes the next trial flow in this case 6090 (6080 + 10) m 3 /s (215,050 ft 3 /s). The plan
repeats the above-mentioned calculations, and obtains the individual scores for this trial flow of 6,090 m3/s
(215,050 ft3/s) for the 2 nd quarter-month of 1947:
Lake Ontario Score for Deviation from Target Level: 32.95
Lake Ontario Score added in Recreational Boating Season: 5.65
Seaway Navigation Score: 2.82
Flow Score for River Upstream of Moses-Saunders Dam: 0.44
Flow Change Score: 0.00
Lac St. Louis at Pointe Claire Level Score: 6.24
Lake St Lawrence Level Score: 1,000.00
Lake Ontario Flow Score for Conditions on the Beauharnois Canal: 0.38
St. Lawrence River at Montreal Score: 0.94
Lac St. Louis at Pointe Claire Level Score Add Boating Season: 0.00
The total score for this trial flow of 6090 m3/s (215,050 ft3/s) is 1,049.42.
200 Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows