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Landmark Cooperation Brings the Colorado River Home

This post is part of a series on the Colorado River Delta. Standing at Morelos Dam, the last in the long line of dams on the Colorado River, and the only one in Mexico, it’s hard not to feel that we humans have betrayed this great river. It has traveled 1,350 miles from its headwaters,...

In most years, little water makes it past Morelos Dam just south of the U.S.-Mexico border, which leaves the Colorado River and its delta dry. Photo by Cheryl Zook/National Geographic

This post is part of a series on the Colorado River Delta.

Standing at Morelos Dam, the last in the long line of dams on the Colorado River, and the only one in Mexico, it’s hard not to feel that we humans have betrayed this great river.

It has traveled 1,350 miles from its headwaters, shared its flow with Los Angeles and Las Vegas, Phoenix, Tucson, and Denver.  It has watered field upon field of tomatoes, melons, alfalfa and cotton.  When it arrives here, it is largely spent:  In a typical year, ninety percent of its flow is gone by the time it reaches the U.S.-Mexico border.Colorado River delta series

As Morelos diverts the remaining ten percent into a canal for delivery to the residents of Mexicali and the farmers of the Mexicali Valley, the heaviness of death takes hold.  From atop the dam, I look south – and see the river is gone.

The Colorado has not reached its lower delta and estuary for most of the last half century.  As giant Lake Powell filled after the completion of Glen Canyon Dam in 1963, virtually no flow passed Morelos Dam for eighteen years straight.  Only El Niño events, which brought heavy precipitation to the basin in the early 1980s and again several times during the 1990s, gave the Colorado the satisfaction of a run to the sea.

But thanks to a remarkable effort of bi-national scientific and political cooperation, the Colorado will once again wind though its delta, nourish native trees along its banks, rejuvenate nursery grounds in its estuary, and greet the salty tides of the upper Gulf of California with its precious sweet water.

A historic agreement signed on November 20, 2012, commits both the United States and Mexico to deliver flow back to the Colorado Delta.

Known as Minute 319, an addendum to the 1944 treaty that defines how the United States and Mexico share the Colorado River, the agreement calls for a five-year pilot program to provide a total of 158,088 acre-feet (195 million cubic meters) of water to the lower river and its delta.

That’s about one percent of the river’s historic annual flow delivered over five years.

Although not a great deal of water, conservation groups on both sides of the border have worked tirelessly for more than a decade to create a “map of the possible” that prioritizes restoration opportunities that can be achieved with additional water.

“There’s a lot of hope that through Minute 319 we will achieve meaningful restoration,” said Osvel Hinojosa Huerta, a National Geographic Emerging Explorer and Director of the Water and Wetlands Program for Pronatura Noroeste, the regional chapter of Pronatura, Mexico’s largest conservation organization. “Minute 319 is a landmark for the restoration of the delta.”

A Shared Commitment

Two thirds of the water committed to the delta will be used to create a “pulse flow” – a slug of water that mimics the natural yearly flood that historically occurred as the Rocky Mountain snows melted and filled the river’s channel.  A periodic pulse flow is essential to scour the channel and floodplain, thwart the growth of salt cedar, and help establish willows and cottonwoods, which require flooding for seed germination.

The other third of the Minute 319 water will create a “base flow’’ that keeps the river corridor wet and flowing.

In a unique alliance, the Mexican and U.S. governments and a coalition of conservation organizations are each responsible for delivering a third of the total water committed to the delta under the agreement.

To fulfill its share, the conservation groups are buying water rights from willing sellers in the Mexicali Valley and banking them in the Colorado River Delta Water Trust – the first water bank in Mexico dedicated to returning water to the environment.

Besides providing flows to the delta, Minute 319 sets out a new formula for sharing the gain from times of surplus as well as the pain of drought. The latter is particularly important since climate scientists expect dry spells to occur more frequently in the Colorado Basin in the coming decades.

Minute 319 also gives Mexico the ability to store water in Lake Mead, the vast reservoir behind Hoover Dam, giving both nations additional flexibility in how they manage the river’s flows.

“Leaving behind unilateralism, the two countries united to sign the most important bilateral Colorado River agreement since the 1944 Treaty,” writes Jennifer Pitt, Colorado River Project Director for the Environmental Defense Fund.  Minute 319 provides for “exactly the kind of innovations that will be needed for both the river and the communities who use it to weather the impacts of climate change.”

The Colorado River approaches the U.S.-Mexico border. Here at Morelos Dam, most of the remaining ten percent of the river's flow is diverted to the Mexicali Valley.
The Colorado River approaches the U.S.-Mexico border. Here at Morelos Dam, most of the remaining ten percent of the river’s flow is diverted to the Mexicali Valley. Photo by Cheryl Zook, National Geographic

This cooperation, which was hard won, not only binds the two nations more tightly together, it opens the door to more creative solutions for managing the limited waters of the Colorado.

“The increased levels of binational cooperation and management flexibility offered by this agreement may well be critical to the future of the region,” said Peter W. Culp, a partner with the law firm Squire Sanders, in an email exchange.  Culp represented the interests of U.S. conservation organizations and assisted U.S. officials during the negotiations.

At the historic signing ceremony for Minute 319 in San Diego, California, U.S. Secretary of the Interior Ken Salazar struck a chord for cross-border and cross-cultural conciliation over river matters into the future.

“We are connected truly as two peoples by our reliance on the Colorado River,” Salazar said. “In fact the Colorado River in so many ways makes us one people.”

A New Day, but Hard Work Remains

The ink was barely dry on the new agreement when the conservation groups so instrumental in bringing this historic agreement to fruition began to plan to ensure its success.  Assuming the flows and restoration projects are producing good results, the bi-national activities would be extended  — and hopefully expanded — through 2026.

While Minute 319 provides a crucial start to revitalizing the Delta, research by Edward P. Glenn at the University of Arizona and others suggests that allocating about one percent of the Colorado River’s historic flow to the river every year (rather than over five years, as Minute 319 does) – and delivering an annual base flow of 30,000-50,000 acre-feet and a periodic pulse flow of about 260,000 acre-feet – are needed to sustain the delta ecosystem over the long term.

Though a humble name, Minute 319 is a grand achievement in international river cooperation: two countries and their conservation communities have come together to give some water back to a long-contested and over-allocated river.

And for the insects and birds and people, trees and fish of the Colorado Delta, it heralds a new day: their river is finally coming home.

Help restore water to the Colorado River by joining Change the Course. Sign up online or text ‘River’ to 77177.

Special thanks to Silk and Coca-Cola, Charter Sponsors for Change the Course. Additional funding generously provided by the Walton Family Foundation.


Sandra Postel is director of the Global Water Policy Project and Freshwater Fellow of the National Geographic Society. She is the author of several acclaimed books, including the award-winning Last Oasis, a Pew Scholar in Conservation and the Environment, and one of the “Scientific American 50.” She is co-creator of Change the Course, the national freshwater conservation and restoration campaign being piloted in the Colorado River Basin.

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Meet the Author

Sandra Postel
Sandra Postel is director of the Global Water Policy Project and author of Replenish: The Virtuous Cycle of Water and Prosperity. From 2009-2015, she served as Freshwater Fellow of the National Geographic Society. Sandra is also co-creator of Change the Course, the national water stewardship initiative awarded the 2017 US Water Prize for restoring billions of gallons of water to depleted rivers and wetlands. The recipient of several honorary degrees, she works to bridge science, policy, and practice to promote innovative ways of securing water to meet both human and ecosystem needs.