Bow River Basin - Water Supply Forecasts

Below-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 74 to 92 % of average. As of April 1, the Bow River basin stands to improve the most in term of water supply compared to last year. 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 April 1 forecasts did not change significantly from last month's forecast for the sub-basins upstream of Calgary as normal to slightly above-normal snowfall was recorded in March. April forecasts for the Elbow and Highwood River basins improved 3 to 4 % as a result of above-normal snowfall in March. Despite good snow accumulations at the higher elevations, below-normal runoff is forecast for the March to September period because the snowpack below 6000 feet is average and the severe antecedant conditions. However, current runoff volume forecasts for this year are 18 to 35% higher than recorded runoff volumes last summer.

The first month of the forecast period has been completed, with March 2002 recorded runoff volumes being the much-below-average, ranging from 31 to 78 % of average. Preliminary data indicates that the recorded March volume set or came very close to setting new historical minimum values for the month. 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 28th lowest in 84-years of record (1912-95).