Water Supply Outlook for Alberta

April 2007

Mountain Water Supply Forecast Summary

As of April 1, 2007, above average natural runoff volumes are forecast for this year (March - September 2007) for the Red Deer, Bow, and Cascade Rivers. Average to above average natural runoff volumes are forecast for the North Saskatchewan, Spray and Kananaskis River basins. Average natural runoff volumes are forecast for the Elbow, Highwood and Oldman River basins. Below average to average natural runoff volumes are forecast for the Milk River basin (Table 1).

Snowpack is above to much above average in the upper Bow, Red Deer and North Saskatchewan River basins, but flooding in mountain basins is driven by rainstorms. However, flood risk this spring and summer is elevated, as snowmelt, wet ground and higher flowing rivers can more easily enable rainstorms to create floods.

Forecasted volumes have increased since March 1 in most basins, due to much above normal precipitation in most mountain areas during March.

Warm temperatures during March resulted in some early melting of snowpack in southern Alberta. For instance, snowmelt is underway three weeks earlier than average in the southern Oldman River basin. Due to the early melt, natural runoff volumes recorded for March were much above average in the Oldman River basin and ranged from average to much above average in the Milk River basin. Recorded volume data is preliminary, due to ice effects, and is subject to change. March volumes in the other basins have not yet been presented due to ice effects on accuracy of the calculations. March - April natural volumes will be available in the May Water Supply Outlook. March volumes are typically a small portion of the yearly total.

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.

For technical enquires about this web page please contact Alberta Environment - Environmental Management Water Management Operations Branch at AENV-WebWS@gov.ab.ca