In early winter, OPG began the annual drawdown of Lake Temagami, as per our standard practice. Our snow survey information (gathered biweekly) was showing lower than normal snow amounts for much of the winter. With this in mind, OPG began reducing flow at Cross Lake Dam on March 19 to begin a slow, gradual refill of Lake Temagami. The refill strategy is based on a cautious approach keeping in mind that there are still several weeks before the summer minimum elevation target and that depending on precipitation received in April and May, we may need to maintain some storage to assist with flood mitigation if we see large rain events through the spring. Our most recent snow surveys indicate that the average water content across the Sturgeon River basin is 4 mm, which translates to 3 percent of normal (snow is pretty much gone).
We have received inquiries about ‘lower-than-normal’ water levels across many of our reservoirs this Spring. In many cases, reservoirs were not drawn as deep as normal, and have already begun refilling; in reality many reservoirs are at or above normal for this time of year. The lack of snow along the shoreline and on the lakes may possibly be leading to a perception of lower than normal water levels. With respect to Lake Temagami, for example, our records indicate that the elevation is actually about 11 cm higher than normal for this time of year based on recorded levels between 1950-2021. The water level is only at this level at this time of year about 15 % of the time (i.e., 85 % of the years in this period have recorded lower levels on April 7).
As a reminder, water level and flow graphs can be found at www.opg.com/river.