Mountain Water Supply Forecast Summary

Despite below to much below average precipitation this spring, early snowmelt due to very warm weather in mid May resulted in above to much above average natural runoff volumes in much of the Bow River basin and at the Bighorn Reservoir, and average to above average natural runoff volumes in the Oldman River basin for the March through May period. However, in areas where snowpack was below to much below average in May, melt has been insufficient to overcome the lack of precipitation, and as a result natural runoff volumes were below to much below average for the March through May period in the Milk, Highwood, Elbow, Red Deer, and remainder of the North Saskatchewan River basin.

With snowmelt occurring a few weeks earlier than usual this year, remaining mountain snowpacks as of June 1, 2006 are generally below average south of Calgary to the border, and below to much below average to the north. However, wet soil conditions from last year's heavy rains provide good potential for runoff from rainfall that may occur this summer. As a result, Alberta Environment is forecasting natural runoff volumes ranging from below average to average for the period between June and September 2006.

Total natural runoff volumes for the water year (March to September 2006) are expected to range from below average to average (Table 1).

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.