Water Supply Outlook for Alberta

August 2004

Oldman River Basin - Water Supply Forecasts

As of August 1, 2004, March to September 2004 natural runoff volumes are forecast to be much-below-average at the Oldman Reservoir and Lethbridge, below to much below average in the Waterton and St.Mary Rivers, and below average in the Belly River (Table 3a). Current forecasted values for the March to September 2004 period for the Oldman River at Lethbridge would rank 17th lowest in 91-years of record (1912-2001). Current runoff volume forecasts range from 61 to 88% of average. The August 1 forecasts for the Oldman Reservoir and Lethbridge dropped by 5% and 1% from July 1 forecasts, while the Waterton, Belly and St.Mary River forecasts are 1-2% higher than last month's forecasted volumes. The March to September 2004 forecast volumes are 3 to 15% higher than those recorded during the same period last year, except at the Oldman Reservoir, which is 9% lower.

The first five months of the forecast period have been completed, with March-July 2004 recorded runoff volumes ranging from 60 to 89% of average. Runoff in the Belly River was below average, below to much below average in the Waterton River, and at all other forecast locations much-below-average. Recorded volume data is preliminary, and is subject to change. The remaining volume forecast, which is the March to September 2004 forecast minus the recorded volume to date, is available in Table 3b. Below-average runoff is forecasted for the August through September 2004 period at all forecast locations.

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