Two fishermen in boats navigate the Magdalena River Basin in Colombia.
BALANCING ACT: On rivers like the Magdalena, in Colombia, TNC is working to find a new equilibrium that supports environmental needs while sustaining traditional livelihoods such as fishing. © Juan Arredondo

Magazine Articles

Saving Great Rivers

Rivers have been hit harder than almost any other ecosystem on Earth. TNC scientists around the world are helping people and nature thrive together.

Summer 2017

Lisa Bramen Journalist


From the snow-covered peaks of the Rocky Mountains to the sere, crackled plains of the Sonoran Desert, the Colorado River is a study in the interconnectivity of humans and nature. Nearly 40 million people depend on the river for clean drinking water, electricity, recreation and agriculture. Thirsty cities, including Denver, Las Vegas, Los Angeles and Phoenix, tap the Colorado, while irrigation has turned vast expanses of desert into the nation’s wintertime salad bowl. In all, the river contributes $1.4 trillion per year to the regional economy and can provide as much as 4,200 megawatts of hydropower, enough for more than three-quarters of a million homes.

Yet that has all come at a tremendous cost to the environment. Since the early 20th century, the Colorado River has been so extensively manipulated that it no longer reaches its original terminus in the Gulf of California. Lagoons once teeming with fish and frequented by jaguars, coyotes and bobcats have become parched arroyos on the edge of the sea.

What happens on one part of a river system has consequences elsewhere: Infrastructure projects fragment the Colorado, interfering with natural processes such as seed dispersal and fish migration. The Colorado pike minnow has seen 75 percent of its habitat disappear because of reduced flow. Reservoirs cool the water, making it less hospitable to native species, such as the endangered humpback chub, that evolved in warmer temperatures. Salts washed into the river from farms affect drinking water and irrigation supplies and harm fish downstream. And the reduced flow of fresh water from the Colorado into the Gulf of California may be contributing to the decline of the vaquita porpoise, the world’s most endangered marine mammal.

A loop of the Colorado River from the air
COLORADO RIVER A 16-year drought was a wake-up call for the seven U.S. and two Mexican states that depend on the Colorado for drinking water, irrigation, electricity and recreation. © Peter McBride/National Geographic Creative

Similar destruction is happening on rivers around the world. Many face additional threats: dirty runoff caused by deforestation that smothers fish spawning grounds; nutrient rich fertilizer runoff from farms that asphyxiates aquatic life; overfishing; and levees that disconnect rivers from their habitat-rich floodplains and worsen flooding downstream. All of this highlights the reality that river health is as dependent on humans as humans are on rivers.

The Nature Conservancy’s Saving Great Rivers program looks at entire river systems—from mountain headwaters to coastal deltas—to find solutions that support both humans and other species. That approach is helping China, Colombia and the United States, among other countries, sustain ecologically vibrant rivers that serve as a foundation for human prosperity and security, providing hydropower and other benefits to humans while supporting healthy ecosystems.

“We’re for healthy, connected rivers,” says Shelly Lakly, the managing director of the Saving Great Rivers program. “One of the biggest challenges is bad infrastructure in the wrong places. We try to guide infrastructure development into the right places, because our science drives us there.”

Irrawaddy River
Ogooue River The Ogooue and its tributaries are surrounded by vast untouched tracts supporting hippos, gorillas and the world’s largest remaining population of forest elephants. © Michael Nichols/National Geographic Creative

Some rivers remain relatively pristine, offering an opportunity for planners to avoid the mistakes made in other river systems. The small Central African nation of Gabon, for example, is home to fewer than 2 million people, plus gorillas, hippopotamuses and the majority of the world’s remaining forest elephants. Its Ogooué River, a wild torrent that drains nearly the entire country, is a conservationist’s dream.

“In the floodplains, there’s a sense of awe that you can be in a boat for hours and see only green,” says Marie-Claire Paiz, director of TNC’s Gabon program. “There are so few places in the world where you can do that.”

Natural resource extraction—especially of oil—has, by and large, provided stability and a good standard of living for Gabon’s citizens, but the government recognizes the need to diversify the economy. The Conservancy is working with the Gabonese government to take a balanced approach to forestry, agriculture and water infrastructure along the river by providing solid science and decision-making tools. The organization recently completed a digital freshwater atlas that combines information about biodiversity with analyses of the threats posed by different land uses.

With nine sites designated as Ramsar Wetlands of International Importance, including several on the Ogooué, Gabon has also enlisted TNC’s help in developing national standards for management of these crucial wildlife habitats. “Here in Gabon, we have an almost-blank slate to do it right,” says Paiz. “This is an amazing opportunity.”

Other rivers have already been dramatically transformed. The Magdalena River basin, in Colombia, contains extensive biodiversity and is the backbone of the nation’s economy—from the major cities of  Bogotá and Medellín to the lowland fisheries that support some of the country’s most economically vulnerable populations.

The Conservancy is restoring floodplains in the Magdalena’s lower elevations, where migratory bird and fish habitat has been degraded by sediment from deforestation and pollution from illegal mining. And as the country emerges from decades of conflict following a historic peace agreement, TNC is providing open-access computer tools to foster informed dialogue on as many as 140 possible new dams in the Magdalena watershed.

The Conservancy’s Magdalena decision-support system, known as SIMA, uses integrated scientific data to simulate the outcomes of various decisions. Users can create scenarios that avoid development in ecologically or culturally sensitive areas, such as archaeological sites or communities victimized by war. Making such information freely available promotes transparency in the development process, says Juliana Delgado, the science coordinator for TNC in Colombia. “Dialogue is possible when [everyone has] the same information.”

Many countries are looking to hydropower to serve the energy needs of growing populations. As of 2012, 70 percent of all renewable energy worldwide was hydropower, and dams are attractive power sources for countries trying to reduce carbon emissions from fossil-fuel power plants. But the drawbacks of new infrastructure, from displacement of communities to habitat fragmentation, are significant.

The Conservancy’s approach, called Hydropower by Design, encompasses the full life cycle of water projects. In many instances, planning for new infrastructure can ensure that it is built in a way that is least disruptive to fish and flows. Where dams already exist, TNC can recommend better ways to operate them. And it’s possible to strategically remove infrastructure that has outlived its purpose and reconnect rivers.

Duck farm in the Irrawaddy River Delta
Irrawaddy River Duck farm in the Irrawaddy River Delta. Proposed dams have threatened one of the world’s most productive freshwater fisheries. © Michael Yamashita

In Maine, TNC joined with the Penobscot Indian Nation and other partners to reopen 2,000 miles of the Penobscot River and its tributaries, removing two dams and building a state-of-the-art fish bypass on a third to promote the recovery of Atlantic salmon and other species. By increasing power generation from the river’s remaining power projects, the state was able to maintain its overall hydropower production.

Even when dams can’t be removed, it is possible to operate them in a more environmentally friendly manner. The Yangtze River basin is home to about a third of China’s 1.3 billion people, the heart of the national economy, and the Three Gorges Dam—the world’s largest hydropower project. The river also provides habitat for black, grass, silver and bighead carp, but after the project was built, the populations of these “four famous carp,” as they are known locally, were nearly wiped out. The Conservancy worked with the China Three Gorges Corporation to time water releases to mimic the natural spring flow, when carp spawn. After several years of timed releases, and the reintroduction of adult fish into the river, data suggest that fish populations are beginning to rebound. The Conservancy is now trying to expand fish-friendly releases to water projects on the Jinsha tributary.

Recently, TNC began discussions with the newly elected government of Myanmar, where the Irrawaddy River supports one of the world’s largest freshwater fisheries. Only about a third of the population has access to electricity, and a slew of proposed dams looms on the horizon. But the new government has signaled that it is “very interested in taking a look at hydropower dams again, and whether they’re truly in the best interests of the country,” says Jeff Opperman, a former TNC scientist.

Back on the Colorado River, where water infrastructure has taken such a massive toll, a multifaceted approach is gaining traction across seven U.S. states and Mexico. Many partners, including the Walton Family Foundation, have come together to show that managing water to restore ecosystems will enhance the river’s total value.

“We believe conservation solutions that make economic sense stand the test of time,” says Kyle Peterson, the foundation’s executive director. “In the Colorado River, that means working with The Nature Conservancy, one of our most important partners in our environment work, and other partners to create the incentives for ranchers, farmers and urban water managers to use water in ways that benefit people and the river.”
Sixteen years of drought have highlighted the need for fresh thinking about long-term water security. “Nearly every drop is spoken for, but the river isn’t providing it,” says Taylor Hawes, the Colorado River program director. To address this new reality, she says, “we’re trying to change the culture of water management to include benefits for our rivers.”

Creative whole-basin approaches can help ensure an ecologically functional system that continues to meet well established human needs. On the Colorado, this has meant modernizing century-old irrigation ditches to reduce wasted water; building stormwater retention basins to provide habitat for migrating birds along an important portion of the Pacific Flyway in Arizona; and designing “water banks” that pay water rights holders to leave water in streams and rivers at critical times for fish. The Conservancy has also worked with state and federal agencies to “re-operate” a number of water projects in the watershed, such as Navajo Dam in New Mexico, to more closely mimic natural flow patterns for the benefit of Colorado pikeminnows, razorback suckers and other endangered fish.

In 2014, the United States and Mexico took a significant step forward by implementing a new water-sharing agreement that, for the first time, included environmental restoration provisions. The two countries sent more than 34 billion gallons of water tumbling into the Colorado River delta for the first time since 1998. That water has jump-started the restoration of cottonwood and willow habitat used by endangered birds and other wildlife (“The River’s Return,” June/July 2015).

Beyond the immediate, on-the-ground benefits in the delta, Hawes notes that the water release was important because it showed that this kind of approach can work. “We can manage the Colorado in a way that meets the needs of communities and farms as well as the needs of the river itself. With a lot of careful thought and the right people coming together, we can find solutions that work for everyone.”

Lisa Bramen is a journalist in New York's Adirondack Mountains. She is a senior editor at Adirondack Life magazine and a co-author of the Explorer's Guide Adirondacks (Eighth Edition).