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An animated side-profile illustration of the Glen Canyon Dam, paired with a cross-section chart of Lake Powell, the associated reservoir, titled, “Summer Temperatures in Lake Powell.” The chart shows Colorado River miles upstream of the Glen Canyon Dam on the x-axis and elevation above sea level on the y-axis. The color of the water shows the gradient of water temperature in Lake Powell from deep (cold, blue-green) to shallow (warm, red-orange). Animation shows average summer water level and water temperature at the dam intake for Lake Powell changing every year from 1968 through 2022. The warm layer of surface water moves up and down with the water level, so when water levels are low, the water temperature at the dam intake is higher. The warmest average summer temperature at the intake was 66.6° F in 2022, when Lake Powell was 25.4% full. The coolest average summer temperature at the intake was 46.7° F in 1992, when Lake Powell was 57.5% full.