New look at old study could correct Colorado River Compact flaw
(CN) — A century ago, seven men formed a commission to decide how water from the Colorado River should be divvied up, basing their allocations on estimates of 16.4 million acre-feet of flow per year. The trouble was — and continues to be — the estimate was wrong.
Today, biological sciences professor Shemin Ge and her colleagues at the University of Colorado Boulder hope decisions made over 100 years ago can be looked at in new light with lesser-known information made and will talk about at a historical presentation in Colorado titled "Learning from History in Reallocating the Colorado River."
“It would be very helpful not to repeat the mistakes in the past to bring science to the table for the discussion,” she said.
Ge and her team offer a historical perspective on the issue and how the over 100-year-old Colorado River Compact might have overestimated the amount of water the river could provide — estimates that were not backed by current surveys or research, she said. They presented their findings Thursday at the American Geophysical Union meeting in San Francisco.
In the early 1900s, the middle section of the Colorado River Basin was one of the most remote and inaccessible regions, making water measurements very difficult to obtain.
At the time, the Colorado River Commission estimated 16.4-million-acre-feet of river discharge annually at Lee Ferry, based on stream discharge measurements at Laguna Diversion Dam near Yuma, Arizona.
But in 1916, U.S. Geological Survey hydrologist Eugene Clyde La Rue had calculated a lower estimate of 15.0 million acre-feet per year after traveling hundreds of miles of the Colorado River and its tributaries between 1914 and 1924. This difference accounts for almost 10% of the river discharge assumed by the men who signed the compact in 1922 and even falls short of the estimated reduction in demand needed to address the current shortage. The U.S. Bureau of Reclamation has said Colorado River Basin states needed to reduce consumption by 2 to 4 million acre-feet in 2023 to protect hydropower generation at Lake Mead and Lake Powell, according to Ge.
The Colorado River Compact has led to a water shortage crisis, with water levels at Mead and Powell reaching historic lows and threatening water supply, hydropower and ecosystems. The water shortages in the Colorado River basin are often attributed to climate change, population growth, and reduced precipitation, but the 1922 commission's decision to ignore hydrologic science during the negotiation of the original compact is a significant factor. As discussions continue and planners negotiate a new compact, they must avoid repeating the same mistakes today, Ge said.
“I think the states and the government are working towards a better agreement for the future,” Ge said in an interview. “So, I think it's important to bring scientists to the table with all parties within the basin to the table. Fifty years ago, or even just 100 is at that time they didn't have much to work with. They know the advanced technology.”
Various interested parties, beyond water researchers and managers, share concerns about the issue, Ge said, including the 29 Native American tribes who live along the river.
“And yet because of lack of infrastructure to use, to take the water where it's needed in the tribal nations, and it's just very hard for them to use,” said Ge.
According to Ge, the time for change is now.
“Many of my colleagues, they didn't know,” Ge said of La Rue’s findings. “I think it is important to spread the words and to disseminate what we learned from the history.”