Water Supply Outlook for Alberta

April 2003

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

Volume Forecast for April 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 2003 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 550,000** 75 58-104 52 16/85 138*** 66/85
Belly River 195,000* 82 57-113 55 20/85 126*** 71/85
Waterton River 480,000* 75 60-103 51 17/85 117*** 59/85
Oldman River near Brocket 741,000* 69 49-102 39 17/85 160*** 73/85
Oldman River at Lethbridge 2,036,000* 71 51-105 44 18/85 187*** 76/85

*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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