Water Supply Outlook for Alberta

April 2010

Water Supply Forecast as of April 1, 2010 - Oldman River Basin (Natural Flows)

Volume Forecast for April 1 to September 30, 2010 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 2010 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 585,000** 81 66-98 50 22/91 49*** 25/91
Belly River 192,000* 80 68-97 58 20/91 70*** 20/91
Waterton River 483,000* 82 63-98 50 23/91 75*** 38/91
Oldman River near Brocket 863,000* 82 57-99 51 29/91 80*** 29/91
Oldman River at Lethbridge 2,301,000* 80 56-98 47 28/91 64*** 32/91

*NOTE: The forecast shown is the March to September 2010 forecast minus the recorded volume to date

** - This value is the natural volume and includes the U.S. share
*** - Recorded 2010 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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