Water Supply Outlook for Alberta

July 2003

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

Volume Forecast for July 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-June 2003 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 176,000** 73 55-116 46 23/85 84*** 22/85
Belly River 68,800* 83 60-138 55 31/85 89*** 27/85
Waterton River 113,000* 64 44-98 41 17/85 71*** 15/85
Oldman River near Brocket 198,000* 76 54-101 49 34/85 81*** 25/85
Oldman River at Lethbridge 574,000* 70 49-109 43 25/85 78*** 23/85

*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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