Glen Canyon, Utah. Hiking in a recently-exposed section of Mountain Sheep Canyon at a location 15 feet below the high-water mark of Lake Powell. Renowned for its spectacular deep and narrow sandstone canyons, Glen Canyon was flooded by the waters of Lake Powell when the diversion tunnels around Glen Canyon Dam were screwed shut in 1963. A recent drought in the West lowered the water level 145 feet below full-pool capacity by the spring of 2005. Two years of above-average snowpack have since raised the level of the reservoir about 60 feet. With increasing demands on the Colorado River, it will take many, many years of above-average snowfall to fill Lake Powell to its normal elevation of 3700 feet above sea level.