Colorado River Map
Colorado River Flow Wet Period
Colorado River Flow Dry Period
Colorado River Diversions
Colorado River
Colorado River Map Cities
Colorado River Dams

Data Sources

River flow volumes: US Geological Survey (USGS).

Diversion flow volumes: US Bureau of Reclamation.

Dams, canals, pipelines, and aqueducts: USGS and
National Geographic. Latest available data shown.

This map was made possible with support from the Walton Family Foundation.

The Colorado River

The Colorado River supplies water for 30 million people. It is one of the most contested, recreated-upon, and carefully controlled rivers on Earth. Diverted under peaks, utilized by turbines that create hydropower, and stored by enormous reservoirs, the 1,450-mile-long Colorado faces growing challenges associated with increasing population, declining ecosystems, drought, and expected climate change. Click on a topic below to learn more.

Balancing Limited Supply With Increasing Demand

The Colorado River Basin is a critical component of North American water supply, providing H2O to 30 million people and thousands of acres of farmland. When Colorado River withdrawals were first allocated among the river basin’s seven states, in 1922, the river held 17.5 million acre-feet (5.7 trillion gallons) of water. However, new science has shown that 1922 was part of an especially wet period. The river now averages about 14.7 million acre-feet per year and is allocated among seven states and Mexico. Water managers are trying to address growing challenges associated with over-allocation, rapidly increasing urban populations, development of unused water rights, and expected climate change. The water levels of the river’s two largest reservoirs—Lake Mead and Lake Powell, stored by Hoover and Glen Canyon Dams—have dropped significantly in recent years, threatening supplies for major cities. In addition, the trapping of silt behind dams also limits the quality and extent of river habitats.

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    Parting the Waters

    Water has always been precious in this arid region, but a six-year drought and expanding population conspire to make it a fresh source of conflict among the Israelis, Palestinians, and Jordanians.

Help Save the Colorado River

You can help restore freshwater ecosystems by pledging to cut your water footprint. For every pledge, Change the Course will restore 1,000 gallons back to the Colorado River.


NG's Freshwater Advocates

  • sandra new headshot.jpg

    Sandra Postel

    Sandra is a leading authority on international freshwater issues and is spearheading our global freshwater efforts.

  • Photo: Jon Waterman at the end of the Colorado River

    Jonathan Waterman

    He's paddled the Colorado River from its headwaters to the delta, in an effort to bring awareness to this mighty river at risk.

  • Photo: Osvel Hinojosa Huerta

    Osvel Hinojosa Huerta

    For more than 15 years, Osvel Hinojosa Huerta has been resurrecting Mexico's Colorado River Delta wetlands.

Find More Inspiration »

Education Resources

  • Photo: pool of water in the jungle.

    Freshwater Collection

    See a selection of over 100 freshwater resources from National Geographic Education.

  • Photo: Colorado River at Lake Powell

    Teacher's Guide

    This guide on Earth's Freshwater provides a solid introduction to freshwater in an accessible and reader-friendly manner.

  • Photo: Colorado River snaking through rocks at Grand Canyon National Park, AZ.

    Freshwater Activities

    Explore the relationships between rivers and early settlement patterns.

  • Photo: Salt River

    American Wetlands

    Get muddy with a wade through states, territories, and commonwealths in this Geo-Story.

Change the Course logoChange the Course: Help Save the Colorado River