Bow River Basin - Water Supply Forecasts

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 88 to 100 % of average. The June 1 forecasts changed significantly from last month's forecast due to a major snowstorm in mid-May. Forecasts in the basin improved by 1 to 10 % from last month's forecast as a result of above-normal snowfall in May. Current runoff volume forecasts for this year are 27 to 45 % higher than recorded runoff volumes last summer.

The first three months of the forecast period have been completed, with the March-May 2002 recorded runoff volumes being much-below-average, ranging from 45 to 84 % of average. Preliminary data indicates that the recorded March-May volumes 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 late spring has resulted in little depletion of the higher elevation snowpack, and as a result, the remaining volume forecast (June to September period) is forecast to be above-average. 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 42nd lowest in 84-years of record (1912-95).