Water Supply Outlook for Alberta

August 2003

Table 3b - Water Supply Forecast as of August 1, 2003 - Oldman River Basin (Natural Flows)

Volume Forecast for August 1 to September 30 Year to date
Locations Volume in dam3 Volume as a % of Average Probable Range as a % of Average Reasonable Minimum as % of Average Forecast Ranking (lowest to highest) Recorded March-July 2003 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 67,800** 68 61-98 50 13/85 76*** 16/85
Belly River 28,500* 79 75-107 70 23/85 85*** 24/85
Waterton River 38,600* 56 50-87 37 11/85 67*** 13/85
Oldman River near Brocket 72,200* 65 61-103 52 23/85 76*** 21/85
Oldman River at Lethbridge 214,000* 64 56-99 47 18/85 70*** 18/85

*NOTE: The forecast shown is the March to September 2003 forecast minus the recorded volume to date

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** - This value is the natural volume and includes the U.S. share
*** - Recorded 2003 natural volumes are preliminary and subject to change

Average is calculated for the period 1912 to 1995

NOTE: There is: a 50% chance that the actual natural flow will fall within the probable range given; a 25% chance that the actual flow will be less than the lower bound of the probable range given; and a 10% chance that the actual natural flow will be less than the reasonable minimum. Actual day to day streamflow conditions may vary throughout the season as a result of the effects of streamflow diversion and reservoir storage.

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