Photo: Man adjusting irrigation dam in Australia

A government official adjusts an irrigation door in southeastern Australia.

Photograph by Amy Toensing

In the developed world there is really nothing natural about the way we get our water. Dams produce hydroelectric power and the reservoirs behind dams store water supplies for the long haul. Infrastructure, such as levees and canals, channel water to our homes and fields, and keep rivers running the course we want them to.

Dams, levees, and canals dot the developing world too. In some areas communities still use ancient water storage infrastructures and rely on centuries-old canals for irrigation.

While most agree that water infrastructure—either large- or small-scale—is critical to human civilization, there is also a theory that much of our large-scale water-related infrastructure—such as dams and levees—is not worth the environmental costs, which include fish kills, altered floodplains, increased flooding, and degraded water quality.

Dam building has experienced a resurgence, while at the same time a dam removal movement is gaining momentum in some areas. Over the last decade, some 430 dams have been removed from U.S. rivers, opening up habitat for fisheries, restoring healthier flows, improving water quality, and returning life to rivers.

Infrastructure may help us deal with the effects of climate change—rainstorms becoming more intense, but less frequent—by providing increased storage capacity and flood control, but we need to find ways to use dams, canals, and levees, that don’t harm aquatic species and ecosystems, and jeopardize our long-term safety.

Fast Facts

  • Since 1950, the number of large dams has climbed from 5,000 to more than 45,000—an average construction rate of two large dams per day for half a century.
  • Globally, 364 large water-transfer schemes move 14 trillion cubic feet (400 billion cubic meters) of water annually from one river basin to another—the equivalent of transferring 22 Colorado Rivers.
  • In the ten years since the Edwards Dam was removed from the Kennebec River near Augusta, Maine, populations of sturgeon, Atlantic salmon, and striped bass have returned in astounding numbers, reviving a recreational fishery that adds $65 million annually to the local economy.


Did You Know?

Large dams now intercept 35 percent of global river flows.

More About Freshwater Engineering

  • Aerial view of Glen Canyon Dam on the Colorado River in Page, Arizona.

    Dams Trigger Stronger Storms

    Scientists have long suspected that dams create their own weather. But now some researchers say dams might also trigger more frequent and fierce storms that could erode these enormous, and often aging, structures.

  • 025560.jpg

    Giant Salamanders Helped to Spawn

    A new program in Japan is helping giant salamanders get past dams built to control flooding so the rare amphibians can lay their eggs upstream. Video.

  • Photo: Aerial view of canyon

    Freshwater 101 Quiz

    Where does water sit around the globe? How is it used to produce everyday goods? Test your knowledge about freshwater.

  • U.S. President Bill Clinton looks at a flooded power plant in the Mississippi- Missouri Rivers near St. Louis 17 July 1993.

    Nuclear Reactors, Dams at Risk Due to Global Warming

    As climate change throws Earth's water cycle off-kilter, the world's energy infrastructure is in trouble—and the U.S. is in particularly "bad shape."

In the Field

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.

Freshwater Advocates

  • Picture of Peter McBride in Kenya

    Freshwater Hero: Pete McBride

    Pete is a photographer and visual storyteller with an emphasis on freshwater conservation.

  • sandra new headshot.jpg

    Sandra Postel

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

  • Photo: Osvel Hinojosa Huerta

    Osvel Hinojosa Huerta

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

For More Inspiration »

Change the Course Infographic


Check out this infographic and learn how you can conserve water and save the Colorado River, as well as other freshwater ecosystems.

Share it with your friends!

Water Currents, by Sandra Postel and Others

More Posts »

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