TEMPERATURE

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Prior to completion of Glen Canyon Dam in 1963, the temperature of water flowing through the Grand Canyon each year was highly variable, ranging from the icy, spring run-off to the warm, 85-degree summer-heated flows. However, once the dam was constructed, the temperature of the water released from the dam - drawn from the depths of Lake Powell and released through the dam's large penstock intakes - ranged for many years between 45 to 50 degrees. With the lowering of Lake Powell, release temperatures have been increased to as high as 57 degrees which has likely led to an increase in the humpback chub and other native fish populations in Grand Canyon.

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Updates The timing of when releases are the warmest and when warm air temperatures have the greatest potential to warm the river has a large influence on downstream river temperatures. The warmest release temperatures occur in late October/early November but the greatest potential of warming the river in Grand Canyon occurs in July and September when air temperatures are the hottest. The reason is that it takes a lot longer to warm all the water in Lake Powell vs the water in the river as it flows downstream. News Mainstem Temperature at the LCR 1990-2015: Temperatures on the Rise

Temperature Gages Colorado River at Lees Ferry Colorado River at 30 mile Colorado River above LCR Bright Angel Creek Colorado River abv Lava Canyon rm66 Colorado River bl rm127 Kanab Creek Havasu Creek Colorado River abv National Canyon Colorado River bl Diamond Creek Colorado River abv Spencer rm246 Reports and Links 2013 Nearshore Temperature Findings for the Colorado River in Grand Canyon, Arizona—Possible Implications for Native Fish 2010 Selective withdrawal and sediment augmentation update Other Stuff TCD Learning Page GCDAMP TCD Page Reclamation TCD Page The 2000 Low Summer Steady Flow Experiment The Fall Steady Flow Experiment