Oldman River Basin - Water Supply Forecasts

Below-average natural runoff volumes are forecast for the March to September 2003 period in the Oldman River basin, ranging from 75 to 81% of average (Table 3a). Current forecasts are slightly lower (by 0.5 to 3%) than last month's due to below-average runoff and precipitation during May. The March to September 2003 forecast volumes are 10 to 34% higher than those recorded in the same period in 2001 and are just under half the volumes recorded last year. Current forecasted values for the March to September 2003 period for the Oldman River at Lethbridge would rank 20th lowest in 85 years of record (1912-95).

The first three months of the forecast period have been completed, with March-May 2003 recorded runoff volumes ranging from 75 to 94 % of average. The remaining volume forecast, which is the March to September 2003 forecast minus the recorded volume to date, is available in Table 3b.