Water Supply Outlook for Alberta

May 2002

Bow River Basin - Water Supply Forecasts

Below-average to average natural runoff volumes are forecast for the March to September 2002 period in the Bow River basin
(Table 4a). Current forecasts in the basin range from 82 to 97 % of average. Current snowpack at the higher elevations is above-average in the headwaters of the Bow River basin and much-above-average in the headwaters of the Kananaskis and Highwood River basins. The May 1 forecasts changed significantly from last month's forecast due to the above-normal precipitation in April. Forecasts in the basin improved 4 to 8 % from last month's forecast as a result of above-normal snowfall in April. Current runoff volume forecasts for this year are 22 to 39% higher than recorded runoff volumes last summer. The May 1 forecasts are 6 to 17 % higher than those produced on February 1 as a result of above-normal precipitation this spring.

The first two months of the forecast period have been completed, with the March-April 2002 recorded runoff volumes being the much-below-average, ranging from 43 to 73 % of average. Preliminary data indicates that the recorded March-April volume set or came very close to setting new historical minimum values for the period due to the very dry conditions and the late melt this year. The remaining volume forecast, which is the March to September 2002 forecast minus the recorded volume to date, is available in
Table 4b.

Current forecasted values for the March to September period for the Bow River at Calgary would rank 38th lowest in 84-years of record (1912-95).

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