Oldman River Basin - Water Supply Forecasts

Much-below-average natural runoff volumes are forecast for the March to September 2003 period in the Oldman River basin (Table 3). Current forecasted values for the March to September 2003 period for the Oldman River at Lethbridge would rank 15th lowest in 84 years of record (1912-95). Current runoff volume forecasts in the basin this year range from 61 to 75% of average. The March to September 2003 forecast volumes are higher than those recorded in the same period in 2001 and are about half the volumes recorded last year. Near-normal precipitation during February in the upper Belly River basin resulted in the forecast here not changing compared to last month's forecast. Forecasts in other areas dropped by 1 to 2% since February 1. Despite average to above-average soil moisture due to last year's much-above-normal precipitation, much-below-average runoff is forecast for the March to September period because of the extremely low snowpack this year in the mountains. Substantial precipitation would impact the forecasted volumes significantly.