It’s been ridiculously hot along the unstoppable shrinking shoreline at Lake Mead. Over the past four days, highs have peaked at a scorching 109 to 111 F (42 to 44 C). Similar heat blasted all up and down the Colorado River Basin, squeezing moisture out of a key water supply for 25 million people in California, Arizona, and Nevada.

(NASA predicts that 20-30 year droughts in the US West will become 80 percent more likely due to human-forced warming. For Lake Mead, the reality of mega-drought appears to already be settling in.)

But these record hot days are just the most recent of many for the river and its water. For over the past 16 years the Colorado River has been assailed by drought. A new kind of mega-drought that has almost certainly been spurred by a human-forced warming of the world. A condition of endemic drying that will likely continue to worsen for the foreseeable future.

Lake Mead Approaching Mandatory Rationing Levels



1072.24 feet — that’s the water level for Lake Mead as of June 21, 2016. It’s about 3 feet below the 1075 mark breached for the first time in the reservoir’s history last year. And if Lake Mead remains below that line by the end of this year, it will mean mandatory cuts to Arizona and Nevada’s water supply.

That could happen either this year (2016) or next (2017) and will almost certainly happen by 2018. In fact, the US Bureau of Reclamation predicts a 64 percent likelihood that Lake Mead will not only remain below the 1075 foot level by 2019, but that it will plunge to as low as 1025 feet at that time.

(Lake Mead may average near or below the 1075 line requiring mandatory cuts in water supplies to Arizona and Nevada this year. Image source: Lake Mead Water Level.)

This level is only 125 feet above Lake Mead’s dead pool line of 900 feet. And hitting such a low water level would result in mandatory water cuts all up and down the Colorado River Basin.

Lake Mead supplies water to 25 million people in Nevada, Arizona, and California. 19 million of these people reside in California alone. And according to the 1922 Colorado River Compact, California retains senior rights to the river’s water supply. What this means is that when there’s a shortage, Nevada and Arizona have to take the first hits. And that’s bad news for the six million people and related industries supported by the river in this region. It means that if the 16 year drought along the Colorado River basin continues — and that will likely be the case due to impacts related to human-caused climate change — then water rationing is almost certain to take effect in Arizona and Nevada over the next few years.

(Weather systems that bring rain to the US Southwest are becoming more rare. Scientific studies indicate that this condition is caused by human forced climate change and will continue to worsen this Century if fossil fuel burning and human based carbon emissions do not halt soon. Image source: Climate Central.)

If the climate change driven drought continues and Bureau of Reclamation forecasts are correct, then hitting 1025 feet at Lake Mead by 2019 to 2022 will result in The Department of the Interior stepping in to take control of Lake Mead’s water management. At that point, all bets are off even for California — which would likely then see a 10 percent reduction in the water provided to it by Lake Mead.

Water Knives in the Hothouse Sun

Scientific studies indicate that factors related to human-caused climate change prevent weather systems bearing precipitation from reaching the US West Coast. This problem is particularly acute for the Southwest, where the most intense drying is expected to occur. In addition, added heat — like the record to near record high temperatures experienced across the Southwest over the past few days — results in greatly increased rates of evaporation. So what rain does fall doesn’t stay in rivers or in the soil as long.

(If you thought the current drought was bad, then this animation will knock your socks off. Loss of soil moisture for the US is ridiculously extreme under business as usual fossil fuel burning in this NASA projection.)

As you can see in the NASA soil moisture prediction measure above, this added heat due to climate change is expected to make currently bad drought conditions absolutely terrible over the coming decades. NASA notes that reductions in fossil fuel emissions help to blunt the intensity of the coming droughts, but that worsening drought conditions will still occur. Considering the current state of Lake Mead and the Colorado River basin, we are likely to see worsening water cuts to communities across the Southwest as climate change related heat and drought conditions worsen.

Links:

NASA

US Bureau of Reclamation

Lake Mead Water Data

Climate Central

Lake Mead Water Level

What Lake Mead’s Record Low Means For California

Lake Mead Helps Supply Water to 25 Million People — And it Just Hit a Record Low

The Water Knife

Hat tip to Andy in San Diego