Mountain Water Supply Forecast Summary

As of May 1, 2006, for the period between May and September 2006, Alberta Environment is forecasting natural runoff volumes ranging from below average to average for the Bow, Oldman and Milk River basins, and below average natural runoff volumes for the Red Deer and North Saskatchewan River basins (Table 1). Forecasts have increased compared to last month's forecasts for most basins.

Mountain snow accumulations as of May 1 in the Red Deer and North Saskatchewan River basins are much below average. Snowpack to the south is generally much better; below average to average in the Oldman River basin and near average in the Bow River basin, except for the Highwood River basin where snowpack is below to much below average. Conditions improved slightly since last month in the upper Bow River basin, but were steady elsewhere. Snow accumulation for the year is essentially complete.

As a result of early snowmelt due to warm weather, and wet soil conditions remaining from last year's heavy rains, natural runoff volumes recorded during March and April were average to above average in the Oldman and Milk River basins, and were above average in most areas of the Bow River basin. In the Highwood, Red Deer and North Saskatchewan River basins, natural runoff volumes recorded so far have been generally below average to average.

Water Survey of Canada has updated their runoff volume data for 2005. Natural volumes calculated based on this data is available in (Table 2). This 2005 data is referenced in the basin forecast tables of this report.

Future precipitation could have a major impact on all the water supply forecasts 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.