Oldman River Basin - Water Supply Forecasts

As of April 1, 2008, near average natural runoff volumes are forecast for the March to September 2008 period for the Oldman, Waterton, Belly, and St. Mary Rivers (Table 3a). Current forecasted values for the March to September 2008 period for the Oldman River at Lethbridge would rank 48th lowest in 91-years of record (1912-2001). Current natural runoff volume forecasts range from 90 to 97% of average. In comparison to March 1 forecasts, this represents a decrease of 2 to 4% of average.

The first month of the forecast period has been completed, with March 2008 recorded natural runoff volumes ranging from 41 to 61% of average. This is due to much below normal precipitation during March and below normal temperatures which resulted in less snowmelt than usual. Recorded volume data is preliminary, due to ice effects, and is subject to change. March 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 3b. The forecast is for near average April to September 2008 natural runoff volumes, as mountain snowpack remains average to above average, even at lower elevations.