The Colorado River is overcommitted – here’s how that happened

Lake Mead, formed by Hoover Dam, is the largest reservoir in the country and critical to the water supply of 40 million people in the Southwest. (Photo by Jordan Evans/Cronkite News)

PHOENIX – In the early years of the 20th century, leaders across the West had big dreams for growth, all of which were tied to taking water from the Colorado River and moving it across mountains and deserts.

In dividing up the river, they assigned more water to users than the system actually produces. The consequences of the so-called “structural deficit” are being felt today, as states sweat through difficult river diplomacy to prop up water levels in key reservoirs on the Colorado, which serves 40 million people.

The seven Colorado River Basin states have acknowledged this “structural deficit” for years, but how did it happen in the first place?

In their new book “Science Be Damned,” authors John Fleck and Eric Kuhn lay out the history of how the river was divvied up.

Using Colorado River water for large-scale farming, housing and manufacturing took “significant investment,” Fleck said in an interview. “It created a situation where the actions of one party could really affect other people using the river.”

In the early 1920s, leaders of the seven basin states (Arizona, California, Nevada, Colorado, Wyoming, New Mexico and Utah) and the federal government met to come up with a deal to share the river. The result of their work became the Colorado River Compact of 1922.

Measuring the Colorado

Dividing up the water first meant measuring the water.

“They had about 20 years of records from actually putting stream gauges in the river and measuring its flow,” said Fleck, a former journalist who is director of water resources for the University of New Mexico’s department of economics. “And the conventional story is: ‘Well, what bad luck. They did the best with what they had at the time, and allocated more water than the river actually has, because they didn’t realize it was an unusually wet period.'”

But Fleck and Kuhn argue it wasn’t just “bad luck.” The subtitle of their book is “How Ignoring Inconvenient Science Drained the Colorado River.” The authors describe how the research existed that would’ve led to a better decision.

“There were scientists who looked at earlier evidence showing that there had been, in fact, big droughts in the late 1800s, and that evidence was simply ignored as an act of sort of political convenience,” Fleck said. “It was much easier to solve the problem if everybody thought there was a lot of water.”

More water meant the compact was easier to sell back home, and no one had to forego their dreams.

Fleck and Kuhn wrote about the efforts of scientist E.C. LaRue of the U.S. Geological Survey, whose duties include gathering “reliable scientific information” to minimize loss of life and property from natural disasters and manage water. LaRue estimated Colorado River levels in part using records Mormon settlers kept of the Great Salt Lake, which isn’t in the Colorado River Basin but is nearby.

According to “Science Be Damned,” LaRue’s research, along with that of another scientist, Herman Stabler, put the average “natural” flow of the river at about 15 million acre-feet a year for the mid-1870s to 1922. That’s remarkably close to the 14.8 million acre-feet a year that scientists say the river provides today. (An acre-foot is an acre of land covered with a foot of water.)

But LaRue’s estimates weren’t really part of the conversation.

Delph Carpenter, a famous lawyer from Colorado, and other politicians ultimately went with more generous numbers: 7.5 million acre-feet for the Upper Basin (Colorado, Wyoming, New Mexico and Utah) and 7.5 million acre-feet for the Lower Basin (Arizona, California, Nevada). The compact accounts for Arizona’s use of its in-state rivers by allocating an additional 1 million acre-feet to the Lower Basin. The 1.5 million acre-feet for Mexico would come in a later treaty.

Ignoring the science

Did Carpenter and others believe their own fiction?

“It certainly appears, based on all the available records that we’ve been able to find, that Delph Carpenter and the others who really wanted big development on the river weren’t knowingly lying. They were sort of engaging in the problem of confirmation bias,” Fleck said. “They really wanted the flows to be big, so they had a way of dismissing LaRue, saying, ‘Well, we really can’t trust that kind of science because we really want gauge records.'”

For the most part, LaRue was simply ignored.

Fleck said river managers didn’t really confront the reality of the river’s lower flow until Congress negotiated the Central Arizona Project, which provides river water to Phoenix and Tucson via a 336-mile canal.

“In 1968 when the Central Arizona Project was approved, Arizona knew that there was not sufficient water to keep that canal full year in and year out,” Fleck said.

He points to testimony from then-Reclamation Commissioner Floyd Dominy, who told a House of Representatives subcommittee that “sooner or later, and mostly sooner, the natural flows of the Colorado River will not be sufficient to meet 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.”

Fleck said Arizona knew that, without augmentation, the river water available for CAP customers would fluctuate.

“And somehow that was forgotten, and Arizona grew to depend on a full CAP canal every year,” Fleck said.

‘Accepting’ the science

The river’s structural deficit is about 1.2 million acre feet each year – enough to cover almost four Phoenixes with a foot of water. As more users actually take their full allocations of water, the imbalance contributes to drops in Lakes Mead and Powell, the Colorado’s two main reservoirs. Declines led to the temporary shortage guidelines signed in 2007 and updated this year.

Today’s negotiators are preparing to tackle the structural deficit in a new agreement that will replace the guidelines, which expire in 2026. Fleck said these modern folks adhere much closer to science than their predecessors did.

“We are much better now at accepting rather than ignoring inconvenient science,” he said. “You see serious analytical work being done within the federal agencies even in the midst of the Trump administration’s attitude toward climate change.”

The truth about the river finally may be too powerful to ignore.