Oldman River Basin - Water Supply Forecasts

As of February 1, 2005, natural runoff volumes for the March to September 2005 period are forecast to be below to much below average, except below average inflows are expected at the Oldman Dam near Brocket (Table 3). Current forecasted values for the March to September 2005 period for the Oldman River at Lethbridge would rank 20th lowest in 91-years of record (1912-2001). Current natural runoff volume forecasts range from 72 to 78% of average. The March to September 2005 forecast volumes are 2 to 10% higher than those recorded during the same period last year for Lethbridge, Brocket and the Waterton River, and 3 to 14% lower than last year for the Belly and St. Mary Rivers.

Warm weather and rainfall during mid to late January, associated with the weather systems that resulted in flooding in British Columbia, caused significant melting of the mountain snowpack in the Oldman River basin. Early melting of the snowpack, outside of the forecast period of March through September, means that forecasts for this period do not include this runoff. Reservoirs were able to store some of this volume, and are currently at above average levels.