Water Supply Outlook for Alberta

July 2008

Table 3b - Water Supply Forecast as of July 1, 2008 - Oldman River Basin (Natural Flows)

Volume Forecast for July 1 to September 30, 2008 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 2008 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 234,000** 99 77-123 66 50/91 103*** 53/91
Belly River 77,700* 95 85-125 69 42/91 94*** 37/91
Waterton River 159,000* 98 76-136 59 49/91 109*** 56/91
Oldman River near Brocket 228,000* 89 69-123 53 45/91 101*** 48/91
Oldman River at Lethbridge 766,000* 94 69-122 54 46/91 101*** 50/91

*NOTE: The forecast shown is the March to September 2008 forecast minus the recorded volume to date

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** - This value is the natural volume and includes the U.S. share
*** - Recorded 2008 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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