Mountain Water Supply Forecast Summary

As of June 1, 2004, Alberta Environment is forecasting below to much-below-average natural runoff volumes in the Milk, Oldman, Bow, Red Deer and North Saskatchewan River basins for the March through September 2004 period (Table 1).

Forecasted March to September 2004 volumes are 7 to 16% lower than those recorded during the same period last year in the North Saskatchewan River basin, 20 to 28% lower in the Milk and Red Deer River basins, generally similar in the Bow River basin, and 4 to 14% higher in the Oldman River basin. Forecasted volumes are greater than the near-record lows recorded during the drought year of 2001. Changes from May 1 forecasts generally ranged from a 5% drop (Red Deer) to a 13% rise (Belly River).

The first three months of the runoff season have finished, with preliminary data indicating March-May natural runoff volumes ranged from below to much-below-average at most forecast points, except average in the Belly River. March-May natural volumes to the Brazeau Reservoir and at Edmonton were the lowest and second lowest on record, respectively. However, May mountain snowmelt was delayed in the Bow, Red Deer and North Saskatchewan River basins, and as a result many mountain stream levels are currently, in early June, near average or better. Runoff to come, during the June-September period, is forecast to be generally below-average in the Milk, Oldman, and Bow River basins, below-average to average in the Red Deer River basin, and below to much-below-average in the North Saskatchewan River basin. These forecasts have improved, many significantly, due to near-normal to much-above-normal precipitation during May.
 

These forecasts assume that precipitation over the summer period will be normal. Precipitation will have a major impact on the summer water supply forecast between now and the end of September. Streamflow volume forecasts will be updated monthly until mid-summer. Check our Forecaster's Comments throughout the month for updated information regarding runoff conditions.