BY ROBERT GLENNON
In the 1920s, the Colorado River Compact divvied up the river’s estimated flow, allocating 7.5 million acre-feet of water to the Upper Basin and another 7.5 million to the Lower Basin. [An acre-foot is enough water to flood one acre of land to the depth of one foot, or approximately 325,000 gallons.] The Boulder Canyon Project Act of 1928, as later interpreted by the U.S. Supreme Court, divided up the Lower Basin’s share, giving California 4.4 million acre-feet, Arizona 2.8, and Nevada 0.3. Then, in the 1940s, a treaty between the U.S. and Mexico granted the Republic of Mexico 1.5 million acre-feet of Colorado River water. All together, these allocations add up to 16.5 million acre-feet.
But in the latter part of the twentieth century, University of Arizona tree-ring scientists determined that the actual flow in the Colorado River at Lees Ferry over the past 500 years is only roughly 14 million acre-feet. Whoops. And things get worse.
So the available 14 million acre-feet are really only 12.4.
Now consider the impact of climate change. In a massive 2012 study, “Colorado River Basin Water Supply and Demand,” the U.S. Bureau of Reclamation concluded that climate change will likely reduce Colorado River flows by nine percent. Other prominent scientists, including Brad Udall, think the actual reduction may approach 20 percent. Even assuming the bureau’s numbers are correct, that reduces the available water in the river from 12.4 million acre-feet to a little over 11.
That’s not all. The same study analyzed how much water farmers would need under warmer weather conditions to grow the same amount of crops. The numbers vary from state to state, but overall it’s about a five percent increase for each one-degree rise in temperature. Because farmers consume more than 80 percent of the Colorado’s water, a temperature rise of three degrees would require 1.5 million acre-feet more water simply to maintain the status quo. Finally, the bureau expects the population in the Colorado River Basin to climb from 40 million to between 49 and 76 million by 2060, depending on growth projection scenarios.
Why, you may be asking, haven’t the wheels come off before now? For two main reasons. First, Upper Basin states have not yet used their full allocations. Second, when lakes Mead and Powell are full, they hold approximately 56 million acre-feet—or four years of average flow. But the Colorado River is now in its 15th year of drought, which has drawn down the levels in lakes Mead and Powell to less than 50 percent.
Lower levels in Lake Powell directly correlate to lower flows through the Grand Canyon, which will impact habitat along the river corridor.
Lake Mead and Hoover Dam water intake towers, as seen from the Arizona side of Hoover Dam, October 2010. Photo by: Wikimedia Commons
That depends on how much water the states use and how much precipitation Mother Nature delivers. What is unmistakably clear is that there is a structural deficit. Every year since 2003, states have diverted more water than has come into the river. The 2012 Bureau of Reclamation study ominously concluded that this deficit could average 3.2 million acre-feet per year by 2060.
Who loses in this game of musical chairs? The Upper Basin states are obligated by the Colorado River Compact to release 75 million acre-feet over a 10-year rolling average. That’s a heavy burden considering that the river’s actual flows are much lower than was believed in the 1920s, compounded by the effects of climate change. As for the Lower Basin, California cut itself a sweet deal in 1968 when it traded its congressional delegation’s support for funding of Arizona’s Central Arizona Project (CAP) in exchange for Arizona accepting the lowest priority for the CAP. Now that the implications of the tree-ring studies have become painfully evident, Arizona rues the day it agreed to this trade.
More recently, Arizona managed to persuade Nevada and Mexico to share a small part of her pain if Lake Mead falls below precise elevation levels, which would trigger shortages shared by all three. Alas, the Bureau of Reclamation expects the first trigger could occur as soon as 2018. Without drought relief, the more substantial triggers may not be far off. The hardest hit users will be non-Indian farmers in Arizona who rely on the Central Arizona Project.
The seven basin states and Mexico have enjoyed harmonious collaboration over the last two decades, in sharp contrast to the bitter litigation that characterized most of the twentieth century. Who knows how long this harmony will last.
Water managers face a daunting task because, in light of climate change, the past is no longer a reliable guide to the future. With clear eyes and steady resolve, water managers should consider employing risk mitigation strategies developed in other spheres, such as insurance, hedge funds, stock exchanges, and commodities markets, options I explore in a recent report, “Shopping for Water: How the Market Can Mitigate Water Shortages in the American West.”
Some states have developed careful water plans to adapt to unreliable water supplies. The Colorado Water Plan, finalized in December 2015, is one good example. The culmination of a 10-year process, the plan used local river basin roundtables to establish supply and demand, project future demand, and craft realistic options for meeting it.
Plans in other states, such as Arizona’s 2014 plan, are stuck in an old way of thinking: there must be some oasis out there that Arizona can tap into to augment its supplies. Even the Bureau of Reclamation, the agency that created most of the West’s massive infrastructure for moving water great distances, has rejected this approach. The bureau is playing a critical role in prodding the seven basin states to work toward realistic policy options.
Yet, prominent western water managers are considering massive programs of cloud seeding, which attempt to induce rainfall by dispersing silver iodide from planes or cannons, even though the scientific community is skeptical of the capacity of cloud seeding to augment precipitation. In 2003, a National Research Council report concluded that “there still is no convincing scientific proof of the efficacy of intentional weather modification efforts.”
Stronger conservation programs and increased reuse offer two viable tools for confronting a drier future. For reuse, consider that the City of Los Angeles’ Hyperion Treatment Plant processes a volume of water equal to the seventh largest river in the United States. Yet, almost all of that water is dumped into the Pacific Ocean. In 2015, prodded by the extreme drought, the city began to consider ways to reuse more water.
Another way to encourage conservation is by pricing water appropriately. Most of us take water for granted.
Another option involves reallocating water from one user to another through voluntary leases or sales of water rights. In 2016, flood irrigation, which is woefully inefficient, is used on more than half the irrigated acres in the West. Farmers could install center pivots, micro-irrigation systems, or sub-surface drip irrigation. But these highly efficient systems are costly, beyond the means of many farmers.
Because it’s the cities (and their people and businesses) that need more water, municipal interests should finance the modernization of farm infrastructure in exchange for the water conserved. It’s a win-win. Farmers grow the same crops but with less water, and cities and businesses get a much-needed boost in their supply.
The specter of water markets alarms farmers and rural communities, as they fear that selling water rights will put an end to their way of life.
But cities only need a small portion of agricultural water. A four percent decrease in agricultural water consumption translates into almost a 50 percent increase in the water available for municipal use.
From an environmental perspective, it’s important to remember that a water transfer simply changes one current use to another. If new growth can’t secure water through transfers, it will get water the old-fashioned way: by making new diversions from rivers, building new dams, or drilling new wells. Few environmentalists want that to occur. Yet it may. A proposal for massive new development in Tusayan could sink new wells into an already overtapped aquifer that nourishes springs and creeks in the Grand Canyon.
We have available, viable tools to provide water to our farms, cities, and industry— even as we protect our environment. What we really need is the moral courage and the political will to act.
Robert Glennon is a Regents’ Professor and Morris K. Udall Professor of Law and Public Policy at the University of Arizona. He is co-author of “Shopping for Water: How the Market Can Mitigate Water Shortages in the American West” and author of “Unquenchable: America’s Water Crisis and What To Do About It.”
EDITOR'S NOTE: The views expressed by Advocate contributors are solely their own and do not necessarily represent the views of the Grand Canyon Trust.
"Rather than chasing a rainbow, it would be better to explore using existing water supplies more efficiently."
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