A Sacred Reunion: The Colorado River Returns to the Sea

Completing a 53-day journey through its Delta, the Colorado River reaches the tidal zone of the Sea of Cortez (Gulf of California). Photo credit: Francisco Zamora, Sonoran Institute, with aerial support from LightHawk.

After coursing through its delta for nearly eight weeks, the fresh waters of the Colorado River have touched the high tides of the salty sea.

It is the first time in sixteen years that the Colorado River, which flows 1,450 miles (2,334 kilometers) from its headwaters in the Rocky Mountains of Colorado  to the Sea of Cortez (Gulf of California) in northwestern Mexico, will have reached its final, natural destination.

This reunion between river and sea is due to an agreement between Mexico and the United States, known as Minute 319, to advance the restoration of the Colorado Delta by releasing a pulse flow and sustaining base flows in a five-year experiment.

The pulse flow, which began on March 23, is now nearing its end.  Scientists had not planned on the river reaching its estuary as part of this grand experiment.  But that it has, is a wonderful bonus.

This confluence of the river and the high tides signals that “improving estuarine conditions in this upper part of the estuary is possible if restoration efforts continue in the future,” Francisco Zamora, director of the Colorado River Delta Legacy Program at the Sonoran Institute, wrote to me in an email.  Zamora took the photos featured in this post on Thursday, May 15, from a low-flying plane operated by LightHawk.

If rivers are born with a destiny, it is to reach the sea.  They carry sediment, nutrients and freshwater from the land to the coastal zones, helping sustain the productivity and abundance of marine environments.

Deltas and estuaries – where rivers and seas connect – are some of the most biologically rich ecosystems on the planet.

Before the big dams and diversions of the 20th century, the Colorado’s nutrient-rich freshwater mixed with the Upper Gulf’s salty tides to create the perfect water chemistry and nursery grounds for Gulf corvina, totoaba, brown and blue shrimp, and other fisheries of great commercial and cultural importance to the region and to the indigenous Cucapá.

But over recent decades, a combination of over-fishing and lack of freshwater in-flow has caused fish populations in the Upper Gulf to plummet.

Since the completion of Glen Canyon Dam in 1963, the Colorado has connected with the sea only a few times – mostly during El Niño weather events that brought unusually large amounts of snow and rain to the Colorado Rockies and the upper watershed.  The last time the Colorado reached the sea was in 1998.

The estuary is now part of a protected biosphere reserve and no-fishing zone, an attempt to give fish – as well as the highly endangered vaquita, the world’s smallest porpoise – a chance to revive their numbers.

The river mingles with the tidal channels of the estuary. Photo credit: Francisco Zamora, Sonoran Institute, with aerial support from LightHawk.
The river mingles with the tidal channels of the estuary. Photo credit: Francisco Zamora, Sonoran Institute, with aerial support from LightHawk.

The pulse flow, which was designed to mimic the Colorado’s natural spring flood, is an experiment of historic political and ecological significance: it is the first time the United States and Mexico have made a conscious decision to give some water back to the river to revive the health and habitats of its delta.

One of the planet’s great desert aquatic ecosystems, the delta once boasted some 2 million acres of lush wetlands teeming with birds and wildlife.

Over the past eight weeks, the pulse flow has brought needed water to active delta restoration sites, where conservation groups have planted hundreds of thousands of cottonwoods, willows and mesquite to begin re-establishing habitats for hundreds of species of birds and wildlife.

Timed to coincide with the germination of these native trees, the pulse is also helping new habitats emerge spontaneously along the river.

On the heels of the pulse flow, the Colorado River Delta Water Trust will provide sustaining base flows made possible by purchasing voluntary leases of water from delta farmers.

[Change the Course – a partnership of the National Geographic Society, Bonneville Environmental Foundation, and Participant Media – has partnered with the Delta Water Trust to help provide these crucial base flows.]

Compared with the natural, pre-dam flow of the river through its delta, the volume of water restored through Minute 319 is small – less than 1 percent of the river’s historic flow. But that flow is being strategically timed and directed to produce the highest ecological benefit possible.  Teams of scientists are monitoring the effects on the hydrology, vegetation, birds and other ecological features of the delta, so that future flow releases can be even more effective.

The pulse flow experiment did not specifically plan on the river reaching the sea.

But against the odds, at least a small volume of the Colorado River has fulfilled its destiny – and made it home.

A close-in look of the Colorado River connecting with a tidal channel in the estuary. Photo credit: Francisco Zamora, Sonoran Institute, with aerial support from LightHawk.
A close-in look of the Colorado River connecting with a tidal channel in the estuary. Photo credit: Francisco Zamora, Sonoran Institute, with aerial support from LightHawk.

Sandra Postel is director of the Global Water Policy Project, Freshwater Fellow of the National Geographic Society, and author of several books and numerous articles on global water issues.  She is co-creator of Change the Course, the national freshwater conservation and restoration campaign being piloted in the Colorado River Basin.

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.
  • Ankylus

    Now, if we can get the Rio Grande flowing all the way to the Gulf of Mexico that would be a good next step.

  • Vance G. Lee

    Oh if there was enough water for everyone. In this era of droughts, providing for water down the Colorado River to the delta is only done by sacrificing other users who also need the water.

    • Vance, just to clarify, no water was involuntarily taken away from anyone who could use it. The water for the five-year experiment is coming from joint (US-Mexico) projects to conserve water and upgrade infrastructure, water sold or leased voluntarily to the Delta Water Trust, and the like. — Sandra

  • Srihari

    People like Vance G. Le don’t understand that we are in the “era” of droughts precisely because of the destruction we bring about to natural ecosystems. If there is an era of drought, it appears to be in our collective intelligence and not just in water.

  • Brian Richter

    Yes, Sandra, a glorious moment, and a remarkable accomplishment for all who sought to return the long-lost river to its sea. Let’s mark and savor this as the beginning of a renewed relationship between people and the planet that sustains us: one that embraces the vision that — if we use water carefully and take only what we truly need — that we can have both prosperity and beauty in our world.

  • Wyatt

    Sandra, this water is coming from a dam somewhere up river. That water is used and saved for droughts. Things like this deplete a water supply somewhere or the river would be reaching the sea every year. When you break or open dams you are reintroducing whatever problem the dam was built to solve.

    • Yes, the water is coming from Lake Mead upstream. Minute 319 allows Mexico to store water in Lake Mead, which it previously could not do. This provides for more flexibility in managing the river. Mexico had some “surplus” water stored in the reservoir. But the more important point is that conservation and efficiency improvements, which the two countries are doing jointly, can free up water for the river without harming any current users. The original “problem” goes back to 1922, when more water was promised to the 7 US states in the Colorado Basin than the river typically carries in an average year. Mexico received its share in 1944, but the river got nothing — until this 5-year experiment.

  • Joe

    This is great news. I have a dim memory of a story about the Vacuita, the world’s smallest dolphin, found in very small numbers only in the north end of the Gulf of California. Is it true that the lack of fresh water coming down the Colorado River has affected fish populations negatively and therefore is one of the factors threatening the little dolphin’s existe-

    • Yes, along with over-fishing and other factors, the lack of freshwater flowing into the upper Gulf of California has affected fish populations and the vaquita, the world’s smallest porpoise, over the decades.

  • Scott

    It’s great to see the beginning of this project go so well. Is NG following or investigating the California Delta and the ‘twin pipe’ project? From appearances, we are just restoring one delta that has been ‘dead’ for a long time and are losing another ‘healthy’ delta at the same time. I dont understand why the Sacramento/San Juaquin Delta issue has not gained a a lot of traction. Please comment.

    • National Geographic and its Change the Course partners are working in the Colorado River Basin. The Colorado River Delta is not dead; we’ve seen time and again that it is very resilient — if we add water, it bounces back. But you are absolutely right to also focus attention on California’s Sacramento-San Joaquin Delta, a rich and yes healthier ecosystem closer to home for you. There’s actually been quite a bit of work done on the Bay Delta, but the growing water demands and complicated water supply planning in California have made its protection hard to achieve, as I’m sure you know.

  • Mike

    The dam serves to provide water to the cities of southern California, as these cities have populations that their own supplies of freshwater are woefull inadequate to support. On another note, the dams were built as a public works projects to help fight unemployment, the Hoover in the 30s and the Glen Canyon in the 60s. Aside from some natural annual flooding, the dams were not built to solve any problems for those who would normally get their water.

    • Just to clarify: the big dams did create many jobs during the depression years and beyond, but they were built because the storage was needed to fulfill the terms of the 1922 Colorado River Compact, which divvied up the river’s water among the seven basin states. The dams provided hydropower and irrigation water, critical resources in settling the West.

  • Blair Houghton

    I’d just like to point out that the sediment reaching the gulf is only coming from the riverbed between the last dam and the estuary. The gulf will probably never again be fed with sediments from the entire Colorado river watershed. Also, the flow of water will be an infinitesimal trickle compared to pre-dam flows, so the stoichimetry of the mixed fresh and sea water will be far more dominated by the sea than before. So this is a symbolic exercise, creating at best maybe a living diorama of the old ecology, not a restoration of the natural state of the upper gulf.

    • Thank you for your comments. The idea is to learn from this first pulse flow experiment and to execute even more effective pulse flows in the future, assuming the two governments continue the delta’s restoration. Yes, the volume of the pulse flow was very small — 0.7% of the river’s historic flow — and much less than this actually reached the sea. We’ll have to see if it is enough to improve some conditions in the estuary. I’m hopeful this is more than a symbolic exercise, and that with adaptive management, there will be good ecological outcomes over time. It’s worth repeating that the main goals of this pulse flow experiment did not include the river reaching the sea: the emphasis was on habitat restoration within the delta. That the river did reach the sea, even in such a low volume, was an added bonus.

  • ScienceGrouch

    Oh don’t worry, the rising sea levels and melting alpine glaciers will reunite the Colorado completely. Hell, melting ice sheets and sea level rise it’ll reunite the tip of Florida with the oceans.

  • Mark Tinsdeall

    Sandra. What an inspiring project! I am fortunate to be involved in similar trials (albeit, on a much smaller scale) in England. We are introducing new flow regimes, including spate flows, from a number of our reservoirs. Flows were set historically for downstream industries, now largely absent. So we are trying to naturalise flows as far as possible (while maintaining water supply) to benefit river ecology.
    One observation, which may resonate, is that people will often accept the status quo, no matter how unsustainable, but then have strong opinions when change is proposed. I guess this shows how passionate people are about rivers.

  • Aaron W

    Very cool Sandra!! Just wanted to say thank you for the article. And thank you so much for your responses in the comment section. Very refreshing to see someone try and contain the comment section to open dialog with articulate, on topic, and well researched responses. Very very rare. Your comments are as interesting and informative as the article itself.
    I can’t imagine the amount of joint effort and organized partnerships that made this possible. Well done!!

  • Greg Hatten

    Hey Sandra – just a note to say I love the way you are responding with posts to clarify points and gently correct mis-statements. Rarely see that kind of follow-up from a writer – very cool. I just finished a trip on the Colorado in replica boats celebrating the 50 year anniversary of the 1964 trip by Martin Litton & David Brower that led to the initiative that stopped Marble Canyon Dam (and several others) from being built. We stopped at the Marble Canyon Dam “site” and walked into the exploratory tunnel that was drilled in preparation for the Dam.
    I will continue to follow your writing and the progress of this project…. nice work. You can read about what we did in a 3 part series of articles I wrote on the Pendleton Wool “Blog”. GH

  • Carrie Ballard

    I am very moved by these photos for some reason, and thrilled to see this positive, joint effort by two countries. To see a river ‘return home’ is astounding. And Sandra Postel, you are wonderful for taking the time to engage in the comments and set us straight. These issues are confusing to us citizens, and I so appreciate your writing to us. And lastly, I live in the Netherlands and would like nothing better than to be able to send you some of the liquid stuff we have everywhere sitting around, falling from the sky, and making us all moldy.

  • Heinrich D. Bag

    I like turtles.

  • Gretchen

    I am fascinated and excited about the reunion of Rio Colorado with El Mar de Cortez. I tried to go see it, drove past Gulfo Santa Clara toward San Luis del Rio Colorado, but wasn’t able to see anything from the ground. Is there anywhere to witness the confluence?? Thank you SO much. GREAT information.

  • ReadandShare

    Thanks for nothing!?!

    Obviously, the failure of the Colorado River to flow into the Sea of Cortez is entirely due to the massive series of dams built by us, the United States.

    I cannot even imagine the world furor if, for example, China were to damn the upper parts of the mighty Mekong River to the extent we have done to “our” Colorado — and causing utter destruction to the Mekong Delta in Vietnam!

    Would any of the readers here go ‘ga ga’ and “thank” China for agreeing to a “pulse stream” experiment? I don’t think so!

    When have we Americans become so arrogant???

  • Bill Johnson

    The saying that “Every journey begins with a single step”’ applies in this case. Once at the viewing window of the BLM Visitor Center on a cold winter day in 1988 a ranger made quite a statement. As we looked down on the Glen Canyon Dam he said “They should take the dam apart and reassemble it on the bluff as a monument to Man’s stupidity and let the river flow.” When Barry Goldwater was asked what was his biggest mistake he said it was his assistance that the Glen Canyon Dam be constructed. The Colorado is greater than the Human Race and will prevail in the long term. Fortunately we have some in government and science with the foresight to help the Colorado River in its time of need. Keep up the good work!

  • Jesús Nájera-Garza

    As you may know, the continent land is rising, or the Sea of Cortez is downing; for the old sea shells sit now at @ 10 to 13 m (30 to 40 ft) above high tide…(Malpica & Ortlieb, 1978…Univ.Nac.Aut. de Méx.)…because Isostasy…

  • Jimmy Griffin

    I have lived in Mexicali for many years and having a bit of extra water in the Colorado delta is great news. But to all who are concerned about water shortages and climate change I say population growth is the main cause which apparently no one is willing to confront. Growth is the main factor in our economies. Saludos Jimmy Griffin

  • beth milligan

    Wondrful job matter fact I want to do more please contact me will work fo free

  • Emma@greenglobaltravel

    Everyone seems to forget what a vital role rivers play. Rivers are a great indicator as to the health of an area.

  • Ken Kellogg-Smith

    Ms. Postal, I can visualize a unique southwestern deepwater shipping canal that can be built that would create a U.S. inland waterway linking the Pacific with the Atlantic via the Gulf of Mexico. The Pacific entry/exit point would be at or near San Diego (e.g., the Tijuana River) with the Gulf entry/exit point at or near Brownsville, Texas (e.g., the Rio Grande).
    In the construction of this inland waterway an intersection would occur at the junction of the inland waterway with the Colorado River. Without regard for the overall practicality of this conceptual infrastructure project, what sort of environmental engineering designs do you think could meld the two waterways? For example, could the construction of brackish water artificial lake, something like Gatun Lake in Panama, be useful, since the U.S. waterway would be brackish water, matching the brackish water of the river delta?
    I’ve travelled the world as a merchant mariner, have sailed in many oceans, and have transited the Panama and Suez canals many times. I sincerely believe a southwestern U.S. inland waterway/canal could be built — especially using existing engineering technologies — and that such a waterway could be a major help in opening up the southwestern states for economic development without creating major ecological damage.
    Your ideas?

  • logan

    Water is good for you

  • Trey Hinton

    Water and turtles are the best yahhh.

  • Roger Svensson

    Thanks Sandra for all your hard work. We have another issue which Californians are facing that is the Salton Sea which will pollute a major part of what is south of it especially our neighbors across the border a solution might be to pulse the Salton Sea using the Colorado especially during those abundant years when we have El Nino conditions. Let’s Let it Flow and restore what is needed.

  • Dolf Johnson

    It should be noted that California could get 100% of ALL it’s water needs by desalination using ~12 SONGS sized reactors. Maybe they should start by eliminating the water they take from the Colorado.

  • Randolf

    Disappointed, y’all be taking water from the North Pole, how else is the dudes up here gun get TURNTED

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