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Lake Mead’s Falling Elevation Levels and Their Connection to Climate Change

Climate change, specifically global warming, has become so much more prevalent in the twenty-first century, and although the average person is much more knowledgeable on the ramifications of global warming, pressing issues closely related to climate change only continue to arise.

Lake Mead and Lake Powell are the two largest reservoirs of the Colorado River, providing water to more than 40 million people, as well as irrigating millions of acres of farmland. But, on May 25th, 2021, Lake Mead fell below the elevation of 1,075 feet. While the lake has dropped to this level a few times in the past, it has recovered shortly after. This time, however, that doesn’t seem to be happening. The US Bureau of Reclamation (USBR) predicts that the lake’s levels will continue to fall through the end of 2022, triggering the first-ever shortage declaration on the Colorado River and impacting the water deliveries for several communities.

The ongoing drought in the western states of the US is to blame for the declining water levels. Less snowfall creates less runoff to feed into rivers, which lead into lakes, and dry soils soak up meltwater to hydrate. Climate change is also to blame, as the Colorado River’s flow has declined by 20% over the past century, with over half that decline attributed to warming temperatures. Lake Mead is 16 feet below its level last year, and only 37% full.

The recent drop in water levels, along with the forecast of further decline, makes it most probable that the USBR will declare a Tier 1 shortage this summer. A Tier 1 shortage would impact Arizona and Nevada, with Arizona receiving the greatest impact based on the 2019 drought contingency plan signed by lower Colorado River basin states — the Central Arizona Project would have its water supply cut by a third due to this plan as it has junior rights to the river’s water. Meanwhile, farms in central Arizona will be hit the hardest because of their lower priority status, while major population centers will be spared. In accordance with the drought contingency plan, California will not be affected by a Tier 1 water shortage. Further sinking of Lake Mead, and a consequent Tier 2 shortage, would result in more cities and tribes receiving water from the Central Arizona Project canal becoming impacted.

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