Mountain Water Supply Forecast Summary

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

May 1 mountain snowpack conditions are below-average to much-below-average and soil moisture conditions are below-average. Forecasted March to September 2004 volumes are 7 to 32% lower than those recorded during the same period last year in the Milk, North Saskatchewan and Red Deer River basins, 0 to 10% lower in the Bow River basin, and 3 to 13% higher in the Oldman River basin. Forecasted volumes are greater than the near-record lows recorded during the drought year of 2001. Changes from April 1 forecasts generally ranged from a 5% drop (Highwood River) to a 1% rise (Waterton River) except for the Milk River where an 8 to 10% drop occurred. Above-normal precipitation is needed to achieve average flow volumes this year.

The first two months of the runoff season have finished, with preliminary data indicating March-April recorded volumes were below-average to much-below-average at about half of the forecast points and near-average to much-above-average at the other half. Mountain snowmelt is occurring about a month ahead of normal, and as a result many mountain stream levels are currently average to above average. However, water levels in these streams will drop earlier than usual this year as a result.

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.