The West’s biggest water supply system is in crisis, with the federal government declaring the first-ever shortage for the Colorado River on Monday. That declaration will trigger cuts for users who rely on Lake Mead, the largest reservoir in the U.S., hitting farmers in Arizona particularly hard.
The water crisis is the result of a number of factors, including a multidecade megadrought fueled by climate change, an overconfident Colorado River agreement for water allocation, and chronic water overuse in some of the aridest states in the U.S.
“Like much of the West, and across our connected basins, the Colorado River is facing unprecedented and accelerating challenges,” Bureau of Reclamation Assistant Secretary for Water and Science Tanya Trujillo, said in a press release announcing the water shortage. “The only way to address these challenges and climate change is to utilize the best available science and to work cooperatively across the landscapes and communities that rely on the Colorado River.
With the West expected to see increasing risks of worse megadroughts this century due to climate change, cooperation and finding new ways of living in the era of water restriction will be vital.
Why the U.S. Declared a Colorado River Water Shortage
It’s been clear for months the West was headed for this moment. But it all came to a head in the latest iteration of the Bureau of Reclamation rolling 24-month studies it writes to project the future of water operations along the Colorado River. Using models and the latest data, it became clear that the water levels were going to drop further at Lake Mead and Lake Powell, the two largest reservoirs in the U.S., into 2022.
The August version of the 24-month study found Lake Mead’s elevation will dip to 1,065.85 feet (324.8 meters, and yes, the study measures to the hundredth of a foot) by Jan. 1, 2022. That will lead to what the agency calls Tier 1 water restrictions for the entirety of 2022. Of the four states that draw water from Lake Mead, Arizona and Nevada will be hit by those restrictions owing to the priority system set up to manage the reservoir. Arizona’s water allocation will be cut by 18% while Nevada will face a 7% reduction. Mexico also draws water from Lake Mead, and the country will see a 5% cut to its yearly allotment as well.
Lake Powell will also be impacted by the water restriction. The reservoir is used to feed Lake Mead—yes, a reservoir feeding another reservoir in the middle of the desert is a thing someone thought was a good idea—and the restrictions will affect how much water is released in Lake Mead. All told, Lake Powell is set to release 7.48 million acre-feet of water or 2.4 trillion gallons of water. A boatload of water, to be sure, but far below what water news site Circle of Blue notes is (well, was) the norm of at least 8.23 million acre-feet.
This Is a Crisis Decades in the Making
Both Powell and Mead have also never been lower since being filled in the 1930s and 1960s respectively. All told, the reservoirs along the Colorado River are sitting at just 40% of their total capacity, a huge step down from the already dire 49% they stood at this time last year.
While the year-to-year drop is extreme, this isn’t just a one-year issue that will pass. It’s been ongoing for decades. Lake Mead has been on a clear downward trend since 2000. That was the last year water levels hit the maximum allowable level on Aug. 1. Lake Powell has similarly declined since 2000, and the last time it was at full capacity was 1986.
The Causes of the Crisis Are Complex—But Mostly Human
The water in the Colorado River is shared between seven western states and Mexico. It’s been completely over-allocated, though. The first compact to divvy up water in the river, inked in 1922, was based on the expectation that the river flowed at a certain rate. However, as a 2010 study helpfully notes, the problem was that “the core gauging of the river came during a period of abnormally high runoff.” Subsequent studies using tree rings and other methods have found the river’s flow is usually much lower.
But the dams and damage were done by the early compact, and they’ve been undermined by a burgeoning population in the driest part of the country. Population growth has continued, with the 2020 Census showing booming populations in the counties around Phoenix, Salt Lake City, and Las Vegas, all square in the drought zone. Cities account for a portion of water usage in the West, though farmers also have water rights in, what I will once again remind you, is one of the driest parts of North America. Those farmers will be hit the hardest by the Tier 1 restrictions on Lake Mead. They will, however, be able to turn to groundwater. That’s a stopgap solution at best and may end up making water scarcity worse.
And that’s because the third part of the water crisis is the climate crisis. The West is in its worst drought in at least 1,200 years. The last one of this magnitude likely led to the collapse of Indigenous civilization in the region. While that drought was fueled by natural shifts in the climate, the current one is being driven at least in part by climate change. The rise in temperatures have turned some winter precipitation from snow into rain, sped up spring runoff, and baked the ground with searing heat waves. A study published last year even found that snow loss is leading to higher evaporation rates, essentially baking in drought and even sucking waters from reservoirs up into the sky. All that has contributed to less water to go around.
The problem extends to other reservoirs in the region as well, which are also sitting at record lows. Newsha Ajami, the director of Urban Water Policy at Stanford University’s Water in the West program, told Earther last month that climate change is a “constant reminder that the system was a badly designed system, and the management we have on top of it was not very well thought through.” The water restrictions put in place this week are the latest sign managers need to get their act together fast in order to avert an even bigger disaster.