Water Supply Outlook for Alberta

January 2007

Milk River Basin - Water Supply Forecasts

Near average natural runoff volumes are forecast for the March to September 2007 period in the Milk River basin (Table 1). Current forecasts in the basin range from 89 to 94% of the median, 18 to 30% higher than volumes recorded during the March through September 2006 period. For the Milk River at Milk River, current forecasted values for the March to September 2007 period would rank 41st lowest in 91 years of record (1912-2001).

This forecast assumes that precipitation over the remainder of the winter period and through the summer period will be normal. The range of possible rainfall scenarios is large. As a result, probable range forecasts and a minimal precipitation forecast of natural runoff volume are also provided in Table 1. At Milk River for example, lower quartile precipitation is currently forecast to result in 35% of median natural runoff volume and upper quartile precipitation is forecast to result in 132% of median natural runoff volume. In the case of extremely low precipitation, natural runoff volume is predicted to be 22% of median. Since more information becomes known over time, streamflow volume forecasts are updated monthly until mid-summer.

Although snowpack is currently ranges from zero in the plains to near average in the higher elevations, it is near the halfway point of the snow accumulation season in this area. Future snowfall, and summer rainfall, will translate into runoff as soil moisture conditions were average going into winter.

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