Water Supply Outlook for Alberta

August 2011

Water Supply Forecast as of August 1, 2011 - Oldman River Basin (Natural Flows)

Volume Forecast for August 1 to September 30, 2011 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 2011 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 119,000** 122 107-144 98 73/91 145*** 82/91
Belly River 57,000* 157 133-162 97 87/91 148*** 89/91
Waterton River 76,000* 123 107-149 74 72/91 127*** 77/91
Oldman River near Brocket 155,000* 144 118-156 84 80/91 153*** 82/91
Oldman River at Lethbridge 424,000* 127 100-143 77 74/91 130*** 74/91

*NOTE: The forecast shown is the March to September 2011 forecast minus the recorded volume to date

** - This value is the natural volume and includes the U.S. share
*** - Recorded 2011 natural volumes are preliminary and subject to change Average is calculated for the period 1912 to 2001

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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