Mountain Water Supply Forecast Summary

As of July 1, 2008, above to much above average natural runoff volumes are forecast for this year (March - September 2008) for most rivers from the North Saskatchewan River south to the Oldman River basin. Average volumes are expected for the Oldman River at Brocket and Lethbridge, the Milk River at Western Crossing, and into the Bighorn Reservoir. Below average volumes are forecast for the Milk River at Milk River and at the Eastern Crossing, and below to much below average volumes are forecast for the Bow River at Banff (Table 1). Forecasted volumes have increased significantly in most basins since the May 1 forecasts were issued, due to much above normal precipitation in most mountain areas during May and June. An exception is the Bow River at Banff, which decreased by 4%.

Natural runoff volumes recorded for March-June were among the twenty highest in up to 91 years of record for the Red Deer, Elbow, and Highwood Rivers, the North Saskatchewan River at Edmonton, and into the Cascade and Brazeau Reservoirs. In other mountain basins, volumes recorded so far have generally ranged from average to above average, except below average to average for the Belly River near Mountainview, below average for the Milk River at Milk River and at the Eastern Crossing, and below to much below average for the Bow River at Banff. Recorded volume data is preliminary and is subject to change.

Average natural runoff volumes are forecast for the remainder of the year (July - September 2008), except above average for the Red Deer, Elbow, and Highwood Rivers and into the Brazeau and Cascade Reservoirs, and below average for the Bow River at Banff and Calgary and the Milk River at Milk River and the Eastern Crossing. Forecasts assume that precipitation over the remaining 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. Check our Forecaster's Comments throughout the month for updated information regarding runoff conditions.