Water Supply Outlook for Alberta

May 2011

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

Volume Forecast for May 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-April 2011 Volume as a % of Average Ranking (lowest to highest)
St. Mary River 692,000** 103 93-123 88 55/91 78*** 33/91
Belly River 231,000* 103 84-114 76 53/91 86*** 40/91
Waterton River 592,000* 108 84-118 78 60/91 71*** 28/91
Oldman River near Brocket 1,225,000* 126 84-147 77 70/91 71*** 32/91
Oldman River at Lethbridge 2,930,000* 111 77-130 71 64/91 77*** 33/91

*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.

For technical enquires about this web page please contact Alberta Environment - Environmental Management Water Management Operations Branch at AENV-WebWS@gov.ab.ca