Water Supply Outlook for Alberta

May 2008

North Saskatchewan River Basin - Water Supply Forecasts

As of May 1, 2008, natural runoff volumes for the March to September 2008 period are forecast to be below average into the Bighorn Reservoir and at Edmonton, at 94 and 85% of average, respectively. Inflows into the Brazeau Reservoir are forecast to be 90% of average, which is below average to average for this location (Table 6a). This represents a 2 to 3% increase since the April 1 forecasts. Current forecasted values for the March to September 2008 period for the North Saskatchewan River at Edmonton would rank 28th lowest in 91-years of record (1912-2001).

Significant precipitation of 30 to 70 millimetres on May 7 to 9 in the area between Edmonton and the two reservoirs may further increase the Edmonton forecast next month, depending how much more precipitation occurs during the rest of May. Precipitation during the first twelve days of May in mountain areas has been generally below normal so far in the Bighorn Reservoir's basin, and normal in the Brazeau.

The first two months of the forecast period have been completed, with March-April 2008 recorded natural runoff volumes at the Brazeau Reservoir being the lowest in 41 years of record at 41% of average. Edmonton recorded natural runoff which was eighth lowest in 92 years of record at 54% of average. Data for the Bighorn Reservoir is not available. Recorded volume data is preliminary, due to ice effects, and is subject to change. March-April volumes typically comprise a small portion of the March to September total. The remaining volume forecast, which is the March to September 2008 forecast minus the recorded volume to date, is available in Table 6b. Forecasts for May through September 2008 are for below average to average natural runoff volumes.

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