Bow River Basin - Water Supply Forecasts

As of July 1, 2006, natural runoff volumes for the March to September 2006 period are forecast to be generally below average to average in the Bow River basin, ranging from below average in the Highwood River and at Banff and the Cascade Reservoir, to average in the Kananaskis River and at Calgary. Inflow to the Spray Lakes Reservoir however, is expected to be above average (Table 5a). Current natural runoff volume forecasts range from 76 to 113% of average in the basin. Current forecasts have risen by 2 to 11% of average since the June 1 forecasts, for Calgary, Kananaskis, and the Spray Reservoir, and dropped by up to 4% of average for Banff, the Cascade Reservoir, and the Highwood and Elbow Rivers. The current forecasted volume for the Bow River at Calgary would rank 43rd lowest in 91-years of record (1912-2001).

The first four months of the forecast period have been completed, with March-June 2006 recorded natural runoff volumes ranging from 78 to 122 % of average in the basin. Volumes thus far have been below average in the Highwood River, below average to average at Banff, the Cascade Reservoir, and the Elbow River, average at Calgary and the Kananaskis River, and much above average at the Spray Lakes Reservoir. Recorded volume data is preliminary, and is subject to change. The remaining volume forecast, which is the March to September 2006 forecast minus the recorded volume to date, is available in Table 5b. Below average to average natural runoff volumes are forecast for the July - September 2006 period, except at the Spray Lakes Reservoir where average to above average inflows are expected.