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If You Understand History, Colorado River Shortages Are No Surprise

While some problems on the Colorado River are the result of drought and climate change, Congress set the course for serious trouble in the watershed decades ago by authorizing the Central Arizona Project.

Written by Eric Kuhn, John Fleck Published on Read time Approx. 4 minutes
A viaduct system brings in water from the Colorado River near Yuma, Arizona.Ken Cedeno/Corbis via Getty Images

With the potential of a Colorado River shortage declaration looming as Lake Mead drops, Arizona is struggling with the politics of who will have to cut their water use, and by how much. As Arizona wrestles, it is important to remember how we got here.

It’s easy to blame today’s problems – an overallocated river and declining reservoir levels – on drought and climate change, and both of these do play a role. But our predecessors knew 50 years ago this was inevitable. In 1968, as Congress debated authorization of the Central Arizona Project (CAP), it was clear there was not enough water to supply the 336-mile-long canal, which diverts Colorado River water. But the federal government, with Arizona’s enthusiastic support and the concurrence of the other six U.S. states in the Colorado River basin, charged ahead.

The objective of the half-century of river development that had gone before had not changed in 1968 – massive dams and canals would supply water to farms and cities, backed by the financial might of the federal government. But the fictions on which the preceding half-century’s water development had been based – enough water for all, and a surplus at that – could no longer be supported by the real-world hydrology of the Colorado River.

Today the Central Arizona Project, pumping 1.5 million acre-feet per year to the farms, tribes and cities of the Phoenix and Tucson valleys, is essential to Arizona’s water supply future. But the record left by the project’s congressional debates a half-century ago is clear. Even before we had an inkling of the implications of climate change, the basin’s leadership understood the CAP’s long-term water supply would be far less than 1.5 million acre-feet. Experts in the 1960s agreed that by 2030 the CAP’s reliable water supply, as the project with the most junior priority on the lower river, would be less than 900,000 acre-feet per year and that in many years its actual diversions would be zero.

A truck sprays water on empty parcels of land at a new housing development on March 6, 2013 in Mesa, Arizona. Growth in the Phoenix area depends on water from the Central Arizona Project. (Justin Sullivan/Getty Images)

It was Floyd Dominy, the legendary head of the U.S. Bureau of Reclamation, who delivered the bad news in 1965 as hearings on the Central Arizona Project began. “Sooner or later,” Dominy told members of the House Subcommittee on Irrigation and Reclamation, “and mostly sooner, the natural flows of the Colorado River will not be sufficient to meet the water demands, either in the lower basin or the upper basin, if these great regions of the nation are to maintain their established economies and realize their growth potential.”

Since the early 1900s, we have repeatedly overestimated how much water the Colorado River could provide. Scientists who suggested otherwise were ignored or marginalized. The negotiators of the 1922 Colorado River Compact believed the natural flow of the river at Lee’s Ferry was 17.5 million acre-feet per year. By the mid-1960s, the reality of the river’s actual hydrology, a natural flow of 15 million acre-feet per year, could no longer be ignored. Absent enough water to fill the CAP canal, the politicians and basin water officials turned to a dreamy fiction. All the basin needed to do was augment the river with a series of canals, pumping plants and pipelines to import water from the Columbia River basin in the Pacific Northwest. If the compact and treaty with Mexico allocated 17.5 million acre-feet, but the river only provided 15 million, they would find 2.5 million acre-feet somewhere else.

But the Columbia basin states blocked that option. Despite the reality that there would be no augmentation, Congress, with the acquiescence of the Colorado River basin, approved the CAP. This guaranteed the situation we have today. The CAP, a project essential to the water supply of one of the fastest-growing states in the nation, has, by legislative design, an unreliable water supply.

It would be easy to blame Arizona for expanding based on the fiction that there was enough water to fill its CAP, but it is not alone. California, too, overbuilt based on unrealistic expectations of a surplus on the river large enough to fill its Colorado River Aqueduct, which provides critical water to millions of people from Los Angeles to San Diego. The managers of these projects now face the politically daunting task of cannibalizing their agricultural neighbors, with the senior rights, to provide the water their customers rely on, a process that is already well underway in California.

In the upper basin, the transmountain diversions that provide water to growing cities on the Colorado Front Range and Utah’s Wasatch Front are in the same situation. Even as others continue to harbor grand plans to export even more water out of the basin, project sponsors try to improve the reliability of their junior rights at the expense of their agricultural neighbors.

This will not get easier. With climate change, we face the probability that the 15 million acre-foot river at Lee’s Ferry we refused to accept in 1968 is now a 13 million acre-foot river, and headed down. The genius of the 1922 Colorado River Compact was a social contract between the faster- and slower-growing basins that enabled the political coalitions necessary to pass federal legislation to develop the river. Today, with the basin fully developed and overallocated, the problem is the reallocation of supplies between agricultural districts with senior rights and cities that, though holding junior rights, require certainty. Can we find a similar social contract between cities, agriculture, tribes and the environmental and recreation communities to allow reallocation to proceed in a manner acceptable to all?

The views expressed in this article belong to the authors and do not necessarily reflect the editorial policy of Water Deeply.

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