Water Supply Outlook for Alberta

June 2003

Bow River Basin - Water Supply Forecasts

Generally below-average natural runoff volumes are forecast for the March to September 2003 period in the Bow River basin (Table 4a). Current forecasts range from 73 to 91% of average for this time of year. The June 1 forecasts for Banff, Spray Lakes, Kananaskis and Calgary are up to 3% lower than last month's forecasts. Current forecasts for the Cascade Reservoir and the Elbow and Highwood Rivers have increased 5 to 10%. The 10% increase at the Cascade Reservoir is due to above-average runoff last month from the storm in early May, which followed a storm in late April. Improved forecasts for the Elbow and Highwood Rivers are due to higher precipitation in these basins during May.

Current March to September 2003 volume forecasts for the Elbow, highwood, and Kananaskis Rivers are more than 30% lower than runoff volumes recorded last year for this period, and 1 to 11% lower elsewhere. Forecasted volumes are 16 to 26% higher than those recorded in 2001. Current forecasted volumes for the March to September 2003 period for the Bow River at Calgary would rank 25th lowest in 85-years of record (1912-95).

The first three months of the forecast period are completed, with March-May 2003 recorded runoff volumes ranging from 87 to 120% of average. The remaining volume forecast, which is the March to September 2003 forecast minus the recorded volume to date, is available in Table 4b.

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