Bow River Basin - Water Supply Forecasts

As of May 1, 2005, natural runoff volumes for the March to September 2005 period are forecast to be below average in the Bow River basin, but below average to average at Banff (Table 4). Current natural runoff volume forecasts range from 76 to 96% of average, 1 to 5% lower than last month's due to April precipitation in the upper basin being generally a quarter to two-thirds of normal. Current March to September 2005 volume forecasts are 1 to 17% lower than runoff volumes recorded during the same period last year, but 2% higher for Calgary and 8% higher for Banff. Current forecasted volumes for the March to September 2005 period for the Bow River at Calgary would rank 37th lowest in 91-years of record (1912-2001).

The first two months of the forecast period have been completed, with March-April 2005 recorded natural runoff volumes ranging from 77 to 136% of average. Banff and the Spray Reservoir recorded much above average natural runoff during this period, while natural runoff was above average for Calgary and the Kananaskis River, average for the Elbow River, below average to average for the Highwood River, and below average for the Cascade Reservoir. Recorded volume data is preliminary, and is subject to change. Forecasts for May through September are for below average to average natural runoff volumes at Banff, Calgary and the Cascade Reservoir, and below average at the other four locations. This remaining volume forecast, which is the March to September 2005 forecast minus the recorded volume to date, is available in Table 4b.