The Slims River, one of the two outlets draining the Kaskawulsh Glacier of the Icefield Ranges, Yukon Territory, Canada, is seen to have a variation in both quality and quantity of discharge. These variations, studied for several 24 hour periods during the summer of 1970, are reflections of both the diurnal ablation pattern of the Kaskawulsh Glacier and of a shift in the glacial drainage, a shift which is thought to be due to ice movements at the glacial terminus. Water quality and quantity was measured at the bridge where the Alaska Highway crosses the Slims River and its delta in Kluane Lake. In addition, several similar measurements were taken on tributary streams entering the Slims River below the glacier terminus. Both sets of measurements show a distinct change during early August, the water quantity decreased by a factor of 3–5 and the quality became decidedly less fresh. The change in quality is considered to be a result of the decrease in the proportion of glacial melt water in the Slims River. The effects these changes in river water may have on sediment regimes in Kluane Lake are briefly discussed.