Oldman River Basin - Water Supply Forecasts

Much-above-average natural runoff volumes are forecast for the March to September 2002 period in the Oldman River basin (Table 3a). Current forecasts in the basin range from 145 to 157 % of the average. The August 1 forecasts varied compared to the July 1 forecasts, as locations that received precipitation in early July saw an increase in the forecast this month, while those that did not receive the precipitation, dropped this month. However, overall changes were less than 10 %. In contrast to the three consecutive years of low volumes, this year's current forecasted values for the March to September period for the Oldman River at Lethbridge would rank ninth highest in 84-years of record (1912-95). Current runoff volume forecasts for this year are two to three times that which was recorded last summer.

Preliminary data indicates that record or near record volumes were observed during the first five months of the forecast period (March-July 2002). All forecast points in the basin indicate that the March-July 2002 recorded runoff ranks in the top eight recorded volumes on record (compared to the 1912-95 data). The Belly River near Mountain View recorded a new record volume for the March-June and March-July 2002 periods. Recorded volumes range from 150 to 162 % of average. The remaining volume forecast, which is the March to September 2002 forecast minus the recorded volume to date, is available in Table 3b.