Get Big Pivots

How disregard of science and facts in creation of Colorado River Compact produced some of the mess we’re now in.


by Allen Best

Driving in the Mojave Desert of California, about 100 miles east of San Diego, you can see a horizontal black line high on the side of a white-washed silo used to store granulated sugar. The black line defines sea level. The nearby town of El Centro is 42 feet below sea level, as is much of the surrounding Imperial Valley, one of the nation’s most productive agricultural areas.

Vegetables, fruit and other crops flourish in the Imperial Valley’s year-round growing season, watered by diversions from the nearby Colorado River. The river was first diverted to the desert’s baked rich soils in 1901. Within just three years 75,000 acres were under cultivation, the brown expanses turned green. Then, in 1904, a river swollen with runoff from melted snow in the river’s Rocky Mountain headwaters stormed out of its bed, as it has done through the ages, and poured into the Imperial Valley for 16 months, creating the Salton Sea.

Top photo: The Colorado River near San Luis Rio Colorado, in the Mexican state of Sonora, was dry in February 2017,  as it has been almost entirely since the 1990s.  It has not carried water to the Sea of Cortez with reliability since the 1960s. Photo/Allen Best

Agrarian ambitions could not abide this unruliness. California wanted a dam to hold back the spring floods, to “conserve” the water, in the language of the era, to put it to human use. Los Angeles wanted the hydroelectric power that could be generated by a giant dam and a new source of water, too. For this giant dam, California needed the treasury of the federal government. And for Congress to approve funding, it needed agreement among at least six of the seven states that share the 242,000 square miles of the Colorado River Basin about how the river’s waters would be divided. That’s what caused delegates from the seven states to a lodge near Santa Fe in November 1922 to negotiate the Colorado River Compact.

Hoover Dam

Hoover Dam, shown here in December 2019, tamed the Colorado River’s floods, allowing the cultivation of farms in the baking soils of the lower basin. Photo/Allen Best

The compact negotiated under the supervision of Herbert Hoover, then the secretary of commerce, allocated 7.5 million acre-feet to the lower basin states, primarily California and Arizona. It also gave a splash of 300,000 acre-feet for Nevada, as Las Vegas then was a railroad-siding town of just 2,300 people. The compact also assured the upper basin states of Colorado, Wyoming, Utah, and New Mexico—those above the Grand Canyon—of 7.5 million acre-feet, despite the fact that nearly all the water originated in those states. They didn’t need the water then. Besides, it was assumed the river would deliver another 5 or 6 million acre-feet on average to Mexico’s claims and cover evaporative losses with a still sizable pail of water to be apportioned by some future agreement.

With this agreement, a political path was cleared for Congress to approve funding for the dam near Las Vegas, later named Hoover, and another dam downstream to aid the farmers of the Imperial Valley. And so began the federally sponsored dam-building spree in the Southwest that continued through much of the 20th century.

But Hoover and the negotiators were wrong, terribly wrong, in assuming the river would deliver an average 20 million to 22 million-acre feet. In “Science Be Damned: How Ignoring Inconvenient Science Drained the Colorado River,” Eric Kuhn and John Fleck deliver withering proof that ample evidence existed even in 1922 of long-term flows that would be less than assumed by the compact’s allocations. That evidence had strengthened substantially when Congress ratified the river compact in 1929. But, they say, the self-deception, continued for many decades as water managers “avoided” asking important questions and “ignored” contrary evidence and even “conjured” a surplus when, in fact, none existed. This faulty premise has been “deeply embedded in decisions that shaped the modern West.”

Marc Reisner’s 1986 book, “Cadillac Desert,” was celebrated for its stinging indictment of the federal government and its Western allies in harnessing the Colorado and other Western rivers. But the late Reisner excused the delegates in Santa Fe for only assuming that water flows in the early 20th century would be the norm. They just didn’t have a longer record, he said. A later history, the 2009 revision by William Hundley of his authoritative “Water and the West,” acknowledged that there had been more information available to Hoover and the state delegates.

Kuhn, the former general manager of a water district that encompasses much of the river’s headwaters in Colorado, and Fleck, a former journalist in Albuquerque, drive deeper. They charge “a lack of humility in the face of their ignorance” of the compact negotiators in Santa Fe. “They didn’t want to ask too many questions about whether the number was right,” they say of a report that estimated 21 million to 22 million acre-feet. “They had conjured up a larger Colorado River than nature could actually provide.”

This wishful thinking continued until the 1960s when, in the the final big carveout, this one for the Center Arizona Project, talk had begun about ways to supplement the Colorado River’s native flows. But Henry “Scoop” Jackson, the senator from Washington, would not abide any talk of diverting the Columbia River. Soon after the Arizona project was completed in 1993, delivering water to Phoenix, Tucson, and the farms between. Since then, the Colorado River has almost entirely ceased to flow into the arm of the Pacific Ocean called the Sea of Cortez. But even by 1981, it was, as the late Philip Fradkin described it in his book published that year, “A River No More.”

Ernest LaRue emerges as the star witness in this story of science ignored. A hydrologist working for the U.S. Geological Survey, he had completed a report in 1916 that Kuhn and Fleck say was a reasonably accurate forecast. It balanced drought in the 19th century against the big water years of the early 20th.

Arthur Powell Davis, the nephew of the famed river explorer John Wesley Powell, and then director of the Reclamation Service, the forerunner of the similarly named agency today, had a vision for massive irrigation. That vision had no room for more modest flows.

Imperial Valley

California’s imperial Valley, as seen here in December 2015, provides plenty of leafy green (and purple) for the nation’s salad bowls. Photo/Allen Best

In 1925, before Congress approved Hoover Dam, another report had been delivered. It, too, delivered “hydrologic reality to bear on the dreams of the boosters,” say Kuhn and Fleck. And it, too, was ignored.

One measure of the gap between projected flows and the reality can be found in the gauging station at Lee Ferry, the site just upstream of the Grand Canyon that serves as the legal divide between the upper and lower basins. There, the Colorado River under natural flows—diversions acknowledged in the accounting—has gained 90% of its water, two-thirds of it from the deep snows of Colorado. Those negotiating the compact assumed flows at Lee Ferry of 17.5 million acre-feet. The drought of the 1930s caused the states to reduce the assumption to 16.27 million acre-feet. In fact, flows as of 2016 after 110 years of measurements showed an average of only 14.8 million acre-feet per year.

The fallacy of the assumption was plainly evident in December when water managers from the Colorado River Basin met in Las Vegas for their annual meeting. Together their agencies deliver water from the Colorado to 40 million people, the majority outside the basin itself, from San Diego to Denver, Albuquerque to Los Angeles. At nearby Hoover Dam, a giant band of mineralized white rock marked the decline of Lake Mead, then 60% empty.

Lake Mead

Lake Mead in mid-December was at roughly 40% of capacity. Photo/Allen Best

The primary problem has been called the “structural deficit,” the various agreements authorizing more and larger straws in the river than the river was able to deliver. It would be worse if the upper basin states, instead of using 4 to 4.5 million acre-feet per year, had used their full allocations of 7.5 million acre-feet.

Efforts have begun to reconcile public policies with science. Under the supervision of the federal Department of Interior, the seven basins states in 2019 adopted plans that gently squeeze water use, first and most concretely in Arizona but in other states also if levels in Mead and its upper-basin sibling, Lake Powell, continue to drop. Nobody seriously thinks this plan goes far enough. In another year negotiating will begin for deeper cuts due for adoption in 2026.

“Science be Dammed” delivers a powerful corrective to the unjustified optimism about flows. Even the plan adopted in 2019 bears the title of “drought,” which generally means a prolonged period of abnormally low rainfall (or snowfall). If drought is a big word, several studies have concluded that heat, not drought, as traditionally understood, explains roughly half the reduced flows in the 21st century. It will likely worsen. “The best science of the first decades of the twenty-first century suggests we don’t know how far below us the floor lies,” says Kuhn and Fleck.

The authors chose not to explore the obvious parallels between the willful ignorance of science a century ago with the deliberate blindness today of many public officials about the mounting risks posed by greenhouse gas emissions. But the comparison is obvious, best captured in their observation that water flows were overstated “because it suited the politics of the moment.” Today’s “politics of the moment” will have their payback, too.

This was published in the March 3, 2020, issue of Big Pivots. For subscriptions, see

Phoenix from an airplane

Metropolitan Phoenix, shown here from an altitude of 1,000 to 2,000 feet, depends greatly upon supplemental water from the Colorado River. Photo/Allen Best

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