Restoring the natural flow of the Rio Grande-Rio Bravo River

Snaking its way through the arid desert of the southwestern United States and northern Mexico, the Rio Grande-Rio Bravo River is a critical lifeline for the region. Responsible for sustaining the region’s fertile valleys, the Rio Grande—also known as the Rio Bravo in Mexico—provides clean water for 15 million people.

The river also safeguards unique biodiversity. Almost half of the region’s native fish species are found nowhere else in the world. And the wetlands sustained by the river are critical habitats for birds migrating across the continent.

Of all the rivers in the world, few have changed so rapidly in so short a time. Prior to the 1880s, the Rio Grande-Rio Bravo was a largely natural, free-flowing river. By the 1930s – just 50 years later – it had been diverted thousands of times to supply water for farm irrigation. Large irrigation channels were sliced into the land to send water to almost 300,000 acres of new farmland.

The impact has been immense, for people and ecosystems. Multiple areas of the river now run dry for substantial portions of the year. Also known as flow depletion, the drying of the river has pushed numerous species to the brink of extinction, imperiling at least 75 species. And the climate crisis is exacerbating the water shortages.

“Water shortages are not good for people or nature,” said Brian Richter, freshwater fellow at WWF-US and an author of the study. “When farmers run short of water they can’t produce the food we eat and they can’t support their families. When rivers dry up, we lose species and the benefits that healthy ecosystems provide.”

The good news is that we know how to address these challenges. Also called flow restoration, bringing back some semblance of the natural flow of the river can safeguard clean water for people while avoiding the loss of the region's unique biodiversity.

For the first time, a study supported by WWF analyzed the full river basin, exploring the impacts of restoring different amounts of natural flow, along with how to make it happen. The research team built a first-ever hydrologic model of the entire basin to show how much the natural river flows have been altered throughout the river’s length. The model was then used to identify how and where the water is being consumed and to design strategies that could allow more water to be left in the river.

By far the largest diversion of water goes toward farming—83% in fact, channeled to around 2 million acres of farmland. It’s important that any steps to restore some semblance of the natural flow of the river either maintain or increase farm revenue. This can be done by growing crops that require less water and are more profitable, such as chile peppers, while also laying fallow—or not using—some existing farmland.

Pilot programs have already started. They provide financial incentives to farmers to temporarily let fields lie fallow. These programs have successfully boosted river flows in critical river segments during dry years, ensuring that endangered species can survive while supplementing farmers’ incomes. The next step is to expand these programs to a larger scale.

“A sustainable future for a river that crosses so many boundaries and is under extreme water challenges in the face of a changing climate requires unprecedented collaboration and compromise,” said Enrique Prunes, manager of the Rio Grande-Rio Bravo for WWF-US and a co-author of the study. “We need to bring everyone together to restore a healthy, flowing river that will help to provide water and resilience for farms and communities as well.”

The next step is to advocate for the Rio Grande-Rio Bravo to be a priority in key federal and state policies, and to leverage public and private funding to support conservation groups and farmers in scaling restoration efforts. Water is life, and together, we can ensure a sustainable future for the people and wildlife who depend on the Rio Grande-Rio Bravo.

Read the full study here.