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.
More About Rivers
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Bottom-feeding fish in the Hudson River have developed a gene that renders them immune to the toxic effects of PCBs, according to new research.
A new study finds that 86 percent of U.S. rivers are impaired, with many no longer flowing the way they're supposed to—and that's changing the mix of fish and other organisms that call them home.
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
Pete is a photographer and visual storyteller with an emphasis on freshwater conservation.
Sandra is a leading authority on international freshwater issues and is spearheading our global freshwater efforts.
For more than 15 years, Osvel Hinojosa Huerta has been resurrecting Mexico's Colorado River Delta wetlands.
Water Currents Blog
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See a selection of over 100 freshwater resources from National Geographic Education.
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