Water Supply Outlook for Alberta

March 2006

Oldman River Basin - Water Supply Forecasts

As of March 1, 2006, natural runoff volumes for the March to September 2006 period are forecast to be average for the Oldman, Belly, Waterton and St. Mary Rivers, except for the Oldman River at Lethbridge, where it is forecast to be below average to average (Table 4). Current forecasted values for the March to September 2006 period for the Oldman River at Lethbridge would rank 39th lowest in 91-years of record (1912-2001). Current natural runoff volume forecasts range from 92 to 97% of average. In comparison to February 1 forecasts, this represents an increase of 1 to 3% of average in the Belly, Waterton and St. Mary Rivers and at Lethbridge, and a decrease of 4% in the Oldman River at Brocket. The March to September 2006 forecast volumes are 4 to 18% higher than those recorded during the same period last year for the Waterton, Belly and St. Mary Rivers, and 14 to 38% lower than last year at Lethbridge and Brocket, where flooding was more prevalent.

Despite generally above average snowpack in the mountains and wet soil conditions due to heavy summer and fall precipitation last year, below to much below average snowpack at lower elevations has decreased the runoff forecasts somewhat.

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