Mountain Water Supply Summary

Due to an extremely wet June in all of the five major water supply forecast basins, forecasts have been discontinued for the rest of this year.

Total natural runoff volumes for the year so far (March - August) range from above average to much above average in the North Saskatchewan and Red Deer River basins, and most of the Bow River basin. Despite the very wet June, natural runoff volumes in the Milk River basin are below average for the year so far due to previous dry months. In the Oldman River basin, natural runoff volumes vary from below to much below average in the south (St. Mary River) to above average in the north (Oldman Reservoir). However, any further precipitation will readily translate into runoff since soil conditions are wetter than they've been in years.

In the North Saskatchewan (Table 1) and Red Deer (Table 2) River basins, preliminary data indicates that natural runoff volumes for the March through August period are among the fourteen highest in up to 91 years of record. Inflow to Dickson Dam is the sixth highest on record.

In the Bow River basin, preliminary data indicates that recorded March - August natural runoff volume in the Highwood River is the sixth highest in 91 years of record, while the Elbow River at Bragg Creek volume ranks twelfth highest and inflow to Lake Minnewanka is 16th highest. Natural runoff volumes in the Kananaskis and Spray River basins are above average for the March - August period at approximately 37th highest (55th lowest) on record. Since June's heavy precipitation did not fully reach into the back ranges of the mountains of the Bow River basin, the recorded March through August total runoff volume for the Bow River at Banff is much below average. Natural flow volume in the Bow River at Calgary is above average, 25th highest on record (Table 3).

The total inflow volume to the Oldman Reservoir (near Brocket) was above average for the March-August period, ranking 26th highest in 91 years of record. In the southern half of the Oldman River basin, natural runoff volumes for the same period were below average in the Waterton and Belly River basins, and below to much below average in the St. Mary River basin. The heaviest precipitation during June fell to the north of these three southern rivers, and several months previous to June were dry. Flows at Brocket, however, have been high enough to result in average natural runoff volumes in the Oldman River at Lethbridge for the March-August period (Table 4).

Natural runoff volumes in the Milk River basin were below average for the March-August period; similar to the St. Mary River basin in that the heaviest precipitation fell to the north and previous months were dry. Volumes in the Milk River basin are approximately two-thirds of average, ranking around the 25th lowest on record (Table 5). However, much above normal June and August precipitation has resulted in a dramatic improvement, since March-May natural runoff volumes were less than a quarter of average. due to

Recorded volume data is preliminary and is subject to change. Check our Forecaster's Comments throughout the month for updated information regarding runoff conditions.