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Colorado River, Meet the Sea

This post is part of a series on the Colorado River Delta. Walking the mudflats of the Colorado River Delta in northwestern Mexico, my feet touch silt and sediment that originated in the U.S. Rocky Mountains, hitchhiked with floodwaters through the Grand Canyon, and then, over the millennia, settled out here as the river slowed...

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

Walking the mudflats of the Colorado River Delta in northwestern Mexico, my feet touch silt and sediment that originated in the U.S. Rocky Mountains, hitchhiked with floodwaters through the Grand Canyon, and then, over the millennia, settled out here as the river slowed and meandered its way to the Gulf of California.Colorado River delta series

The delta defies all political borders and human constructs.  Left to flow naturally, the Colorado River system is a connected and unified whole.

If a river is born with a destiny, it is to reach the sea.  It carries sweet water, sediment, and nutrients to the coastal zone, where fisheries and marine life depend on it for sustenance and habitat.  To disconnect a river from the sea is as consequential to the health of the ecosystem as it is to block the flow of blood to a vital organ in the human body: the whole suffers, and may die.

These thoughts roam my mind as the shoreline of El Golfo de Santa Clara, a small fishing town on the northeastern coast of the Gulf of California (also known as the Sea of Cortez), recedes from view.  In a small, motorized boat, we are heading northwest into the Colorado River estuary.

There, before the big dams and diversions upstream, the river’s nutrient-rich freshwater mixed with the Gulf’s salty tides to form the perfect water chemistry and nursery grounds for Gulf corvina, totoaba, brown and blue shrimp, and other fisheries of commercial importance to the region’s economy and of cultural significance to the indigenous Cucapá.

But today no one is fishing in the estuary.  It is illegal.  The dozens of fishing boats that left El Golfo at dawn all headed south.  The estuary is now part of a protected biosphere reserve and no-fishing zone, an attempt to give the fish – as well as the highly endangered vaquita, the world’s smallest porpoise – a chance to revive their numbers.

A Rich Estuary

The Gulf corvina, totoaba, and vaquita are found only in the Gulf of California; all three are extremely vulnerable to extinction.  Historically each winter, adult totoaba, which can weigh up to 200 pounds (91 kilograms), migrated northward along the eastern coast of the Gulf to the estuary and delta, where they remained until spawning in spring.

I keep my eyes peeled for a surprise spotting, but no totoaba appear.

We stop the boat and climb up a bank.  We are calf-deep in a beautiful grass that gives a green hue to the mudflats along this portion of the Sonoran coast. It is nipa, the ancient grain of the Cucapá – and what biologists now call Distichlis palmeri, or Palmer’s saltgrass.

It, too, has suffered along with the fisheries from the absence of the Colorado’s flow.  The saltgrass needs an inflow of freshwater to reproduce.  It used to grow waist-high and yield a tastier and more nutritious seed.  But without the pulses of freshwater, the native grass is stunted, less dense and lacking in flavor.

Back in El Golfo, we meet up with a fisherman, José Armando Sánchez Olivares, who has fished in the Gulf for more than a quarter century. A strong man, who has seen many hard-working days on the sea, he speaks of concern for his community and the livelihoods that sustain it.  Fish catches and incomes have declined, he explains, and people are going elsewhere to find jobs.

Sanchez Olivares is aware of the new bi-national commitment to give some water back to the delta, and of the possibility it creates for the Colorado River to once again reach the sea.

“If we see the Colorado River flow again,” he says, “we are going to feel stronger; our town will have the will to carry on.”

The Gift of El Niño

More research is needed to determine the quantity, quality, and timing of freshwater flows needed to rejuvenate habitat for the fisheries of the upper Gulf.  But after the flood pulses that occurred several times during the 1990s, when El Niño weather patterns delivered high precipitation to the Colorado Basin, scientists documented an increase in the Gulf corvina population.  Shrimp harvests, too, got a boost after river flows reached the estuary.

Ecologist and nature writer Gary Paul Nabhan describes vividly what he saw when flying over the delta after the El Niño-driven flood pulse of 1993.  His words speak of the resilience of life in the upper Gulf (the Alto Golfo) when freshwater flows return:

I did not recognize how important such nutrients and freshwater flows were to the productivity of the marine community until I flew over it during the winter of 1993, when nearly 5 billion cubic meters of water entered the Alto Golfo due to unusually high winter rainfall regimes triggered by El Niño…. I saw the most remarkable biological phenomenon I had witnessed over my entire life. Huge algal blooms and huge eelgrass yields had stimulated invertebrate reproduction and a resurgence of corvina to the degree that we could see massive green patches out in the sea, streaming with enormous schools of fish. Thousands of dolphins and even whales had congregated around each of these patches of productivity. A feeding frenzy was going full tilt, the likes of which the Alto Golfo had experienced perhaps only five times over the previous thirty-five years.

The magnificent display Nabhan witnessed occurred just twenty years ago, long after the dams and diversions had begun siphoning off the yearly influx of water and nutrients so crucial to the Gulf’s fisheries.  In this instance, El Niño was the benevolent provider.  But it is unreliable: fifteen years have passed since a pulse of freshwater has reached the estuary and Upper Gulf.

The future of the fisheries, the town of El Golfo de Santa Clara, and the native saltgrass that sustained the Cucapá – as well as the rich diversity of birds and wildlife that thrive in the delta’s remnants wetlands – depend on whether the Colorado River is allowed to fulfill its destiny and once again reach the sea.

The answer is now largely in our hands.

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.