Hydrologist Shemin Ge emphasized the need to learn from past mistakes in managing Colorado River water resources.She highlighted the overlooked work of Eugene Clyde LaRue and urged the inclusion of scientific data and indigenous perspectives in revisions to water allocations by 2026 to address current challenges and the impacts of climate change.
When it comes to the Colorado River, history tends to repeat itself, but it doesn’t have to.
That's the revelation from University of Colorado Boulder hydrologist Shemin Ge, who recently presented a little-known history of the Colorado River at the American Geophysical Union (AGU) meeting in San Francisco.
The story of hydrologist Eugene Clyde LaRue may help explain the water crisis currently facing many states in the Western United States, Ge said.
Ge's speech centered on a decision made in 1922, when the seven men who made up the Colorado River Commission reached an agreement on the allocation of water from the Colorado River. The Colorado River meanders more than 1,450 miles through seven states. The committee relied on estimates from the U.S. Reclamation Service that 16.4 million acre-feet of water flows through Lees Ferry, Arizona, each year. (One acre-foot is equal to the amount of water required to submerge one acre of land by 1 foot).
But, Ge said, the committee also failed to consider a second, less convenient study conducted in 1916. LaRue, who works for the U.S. Geological Survey, calculated based on his own field data that the Colorado River discharges only 15 million acre-feet.
"It's curious how such good work could have been overlooked at the time, whether by design or ignorance," said Ge, a professor in the Department of Geological Sciences at the University of Colorado Boulder. She worries it could happen again.
In 2022, Lake Mead and Lake Powell, the two main reservoirs on the Colorado River, dried up to an unprecedented extent, and there were concerns that the two reservoirs may enter a "dead pool" state - water can flow into the reservoir, but cannot flow out of the reservoir.
Currently, the seven states in the Colorado River Agreement are working to revise a series of agreements and guidelines by 2026. Ge hopes that this time around, leaders will work closely with scientists and a range of community members, particularly indigenous groups, to develop a rivers law that takes into account the amount of water that actually exists in the West now and in the future. That will become even more important as climate change continues to melt the West's dwindling snowpack, she said: "We can learn a lot from history to improve our water management. Right now, I don't think we're doing enough."
She first learned about LaRue’s story from Eric Kuhn and John Fleck’s 2019 book “Science Be Dammed.” This summer, she and her colleagues wrote about their reflections in the magazine Eos.
This can be seen as a tale of two estimates. Beginning in 1914, LaRue traversed most of the river and its tributaries on foot, collecting first-hand data on the water's flow. This includes measuring the depth and flow rate of river water. "We still do this in introductory geology courses," Ge said. "Low tech but elegant".
In contrast, the Colorado River Commission, headed by U.S. Secretary of Commerce and future President Herbert Hoover, relied on less rigorous research in arriving at its estimate of 16.4 million acre-feet: measurements were taken at just one site near Yuma, Arizona, several hundred miles south of Lees Ferry.
"They used a larger number," Ge said. "A larger number may make allocations easier to negotiate because there is more water to allocate." Today, the 40 million people who rely on the Colorado River for water supply may have to pay the price.
Learn from history
Today, studies show the Colorado River flows at about 13 million acre-feet per year, making LaRue's modest estimate look like fantasy.
However, the Colorado River Compact still allocates water based on a value of 16.4 million acre-feet: Colorado, New Mexico, Utah and Wyoming combined hold 7.5 million acre-feet. Arizona, California and Nevada also received the same amount, while Mexico reportedly received 1.4 million acres.
Ge hopes that by 2026, the seven states will be able to do what Hoover could not — use the best available science to make realistic estimates of river flows decades from now. She added that indigenous groups need to be an important part of the process. In the American West, several tribes hold some of the highest priority water rights but lack the infrastructure to capture a large share of them.
"We don't talk enough about the amount of water in the Colorado River," Ge said. "We talk about drought, infrastructure and water conservation. But shouldn't the first priority be to look at how much water we actually have? It's much less than we thought."