Lower Colorado River Habitats

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The Colorado River and its tributaries—which support 40 million people, sacred Tribal lands, a $1.4 trillion economy, more than five million acres of farms and ranches, and thousands of species of wildlife—are shrinking due to climate change and overuse.

This water system flows through the region known as the Colorado River Basin. The River originates in the Upper Colorado River Basin (spanning parts of Wyoming, Utah, Colorado, and New Mexico), continuing downstream through the Lower Colorado River Basin (parts of Nevada, Arizona, and California) before entering the Colorado River Delta in Mexico (parts of Sonora and Baja California). Historically, the Colorado River flowed all the way into the Gulf of California. Drought and over use have diminished the Colorado River and now it  only occasionally makes it to the Delta . 

Important habitats exist and have been intentionally reestablished along more than 400 miles of the Colorado River that flows south of Hoover Dam. These gems in the desert support countless bird and other wildlife species and offer recreational access.

As we continue to manage the stressed Colorado River, it is vital that we remember and protect these special places, for birds and people.

Habitat is essential and when it is restored, birds and other wildlife thrive. Along the Lower Colorado River, restoration work has focused on four habitat types: cottonwood-willow gallery, mesquite bosque, marsh, and backwater.   

Restored cottonwood-willow galleries, mesquite bosques, marsh, and backwater habitats support many wildlife species. Click on the images below to learn more about some of the bird species that call these places home.

A deeper look at some of the sites along the Colorado River from the Hoover Dam south to the Gulf of California.

For more than 100 years, the Law of the River (the bundle of state and federal laws, international treaties, and court decisions that govern the Colorado River) has prioritized taking water out of the river over protecting river habitats. The U.S. Bureau of Reclamation (Reclamation) operates major Colorado River dams and reservoirs.  

By 2026, Reclamation will adopt a new set of rules, known as the  Colorado River Post-2026 Operations.  They are expected to establish rules for Colorado River water users to use less Colorado River water as the river is shrinking due to climate change and overuse. 

The  operational rules will : 

• Update and expand management guidelines for Colorado River reservoirs, particularly for Lake Powell and Lake Mead 
• Provide Colorado River water users more predictability of the amount of annual water available in future years under anticipated increasing variability, low runoff, and low reservoir conditions 
• Provide additional mechanisms for the conservation, storage, and delivery of water supplies in Colorado River reservoirs 
• Provide new or enhanced opportunities for Basin Tribes to benefit from their water rights 
• Provide flexibility to build resilience and accommodate future needs and growth that are supported by Colorado River water supplies, including the integration of unquantified tribal water rights once they are resolved. 

Audubon is engaged in the new guidelines process because existing rules for sharing the river leave water users at risk of extreme shortages and leave many of the river’s ecosystems vulnerable to losing water when and where they need it—meaning habitat loss for the hundreds of bird species that depend on these oases in the arid West.  We know that future management will need to stabilize water supplies and avoid catastrophic water shortages to communities that depend on the Colorado River, provide a more meaningful way for Tribes to participate in Colorado River management, and intentionally support these habitats if they are to survive climate change.  

See the timeline below for an overview of the Colorado River Post-2026 operations process, including Audubon's comments.