The reconstruction of past streamflow events is of great interest to the water resources engineer to obtain the best possible estimates of extreme flow conditions for investment, decision making, and design. The tree ring data offer a unique way of addressing this problem. The pattern of growth rings of a tree reflects the environmental conditions experienced during each year. Tree rings are produced annually and can be precisely and reliably linked to climatic variations, which makes them ideal for correlation with annual climatic records. This paper demonstrates the utility of using the methods of dendroclimatology, the study of climate through tree rings, to extend streamflow records. The techniques developed were applied to the Athabasca River at Athabasca. The results reveal considerable benefits from the reconstruction through more precise, and more extreme, estimates of drought quantiles.