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Cooperation Along the Colorado River

  “Climate is always changing, but from here on out it is definitely changing,” Jonathan Overpeck told the packed room at the Aspen Environment Forum in Colorado this past weekend. Overpeck is the director of the Institute for the Environment at the University of Arizona, and an expert on water in the West. Aspen leaves...

Picturesque Maroon Lake, created by glaciers during the last Ice Age, feeds a small tributary of the Colorado. Photo: Brian Clark Howard


“Climate is always changing, but from here on out it is definitely changing,” Jonathan Overpeck told the packed room at the Aspen Environment Forum in Colorado this past weekend.

Overpeck is the director of the Institute for the Environment at the University of Arizona, and an expert on water in the West.

Aspen leaves could be seen quaking in the mountain breezes through the narrow clerestory windows at the Aspen Institute, as National Geographic writer Michelle Nijhuis moderated a panel called “Prospects for Water in the West.”

Overpeck pointed out that the Colorado River Basin is home to nearly 40 million people in the U.S. and Mexico, including some of the region’s largest cities. It is also the fastest growing part of the country, with some states having doubled their populations over the past few decades.

Osvel Hinojosa-Huerta, the director of the water and wetlands program with Pronatura Noroeste in northern Mexico, said the Colorado River is already over-allocated by 16%. Hinojosa-Huerta was recently named a National Geographic Emerging Explorer.

Overpeck added that this situation is likely to worsen as the region gets hotter and drier, as predicted by the leading climate models.

According to the 1922 Colorado River Compact (itself part of a body of state, national, and binational regulations collectively called the Law of the River), the Colorado’s water is allocated to seven U.S. states by a precise formula. A binational agreement was added in 1944, granting Mexico 10% of the river’s flows, while the U.S. states have unequal portions of what’s left.

According to Overpeck, the Compact assumed a total flow of 16.5 million acre-feet of water a year. However, he said recent research at the University of Arizona, based on tree-ring studies, suggests the average flow for the 20th century was only 15 million acre-feet. Going back to 800 AD, the average flow was only 13 million acre-feet.

Overpeck added that “megadrought” years of only 10 million acre-feet were “not uncommon.”

“Subtract 20% from that for projected climate change and that’s 8 million acre-feet. That may be the new normal we have to prepare for,” said Overpeck, echoing the theme of this year’s Aspen Environment Forum, “Living in the new normal.”

Dry Mouth

Hinojosa-Huerta pointed out that the last time the Colorado River really reached its mouth was 1988, when there was a particularly wet year.  As a result of the over allocation of its waters, the once rich delta is largely parched, some of it resembling a desert.

“The good news is it is resilient, and with occasional flows part of it maintains its health,” said Hinojosa-Huerta. He said the delta is the primary habitat for an endangered rail, as well as a critical stopover for hundreds of thousands of migrating birds.

Hinojosa-Huerta has been working with a diverse group of partners (including the Environmental Defense Fund, The Nature Conservancy, academic institutions, and others) on both sides of the border to return some of the Colorado’s water “to the environment.” Historically, the environment was not given any allocations of water, but recent binational negotiations are set to change that, Hinojosa-Huerta said.

Pronatura Noroeste and partners have set up a water trust that ensures its shares of H20 will flow toward the delta, to nourish the vegetation and animals that depend on it. The group is buying up water rights from retiring farmers and others along the river’s course, doing reclamation projects that restore tributaries, and working with large users to get graywater.

“We try to get our hands on any water we can for the environment,” said Hinojosa-Huerta.

“Creative Collaboration”

Photo: Maroon Creek in Colorado near Aspen and Maroon Bells
Maroon Creek, which has flowed for 10,000 years thanks to snow melt, says local guide Paul Anderson. Photo: Brian Clark Howard

David J. Hayes, deputy secretary of the U.S. Department of the Interior, called recent talks on the Colorado a “fascinating exercise in governance.” He added that the river’s flows are actually “fairly modest.”

Hayes said, “It’s not the Mississippi, but it is the water supply for 40 million Americans and Mexicans. There has been more creative collaboration on the Colorado in recent years than over the past century.”

Hayes said states have been working on banking water for each other in traditional reservoirs, but increasingly in newer ways, such as underground, to reduce evaporation and avoid some of the controversy around big dams (see a dramatic video of a dam coming down). He added that there are currently talks to save some water for Mexico. Hayes also said the U.S. government has been working to improve water access to Navaho and Hopi communities.

According to Hayes, California (which gets 58.7% of the flows allocated to the river’s lower basin), has been working hard to decrease its water use, which had crept up above its limits.

He added that the state is still taking too much water from the Bay Delta (the delta of the Sacramento-San Joaquin River), which is in danger of crashing ecologically.

Hayes also added that the U.S. government is investing in research into the effects of climate change on the region, including studying the “pressure points.” He said, “When the real crunch time comes do we have the tools we need? This is one area of the country where you can talk about climate change and not be hooted because people see it.”

Still, Hayes added, “We have got to be better at river management. No one owns rivers; we’ve got the Army Corps of Engineers and the Bureau of Reclamation in many cases, but for many rivers there is no federal involvement.”

Hayes said there is still a lot of inequality along the river. In California’s Imperial Valley, farmers pay $15 an acre-foot for water, but down in Los Angeles the city pays $400 an acre-foot for the same water.

The Colorado supplies a third of the water used along sunny Southern California’s coast, where 19 million people live. If a big earthquake knocks out a few key pumps, it could spell a severe shortage.

The panelists at Aspen agreed that there is more cooperation along the Colorado than they have seen in a long time, although there is still a lot of work to do, to make sure everyone gets enough, from the biggest city to the smallest aquatic insect.


Brian Clark Howard is an Environment Writer and Editor at National Geographic News. He previously served as an editor for and E/The Environmental Magazine, and has written for,,, Yahoo!, MSN, Miller-McCune and elsewhere. He is the co-author of six books, including Geothermal HVACGreen Lighting and Build Your Own Small Wind Power


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