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Rivers and Lakes

Reducing the Ecological Impact of Dams

The Conservancy believes that it is important to engage with decision-makers in an effort to minimize the environmental and social threats posed by these projects.

Every person requires access to fresh water to survive. Beyond our direct need for drinking water, water is critical to the global food supply and in meeting our energy needs. To serve these multiple demands, more than 45,000 large dams and an exponentially larger number of smaller dams have been constructed on the world’s rivers.

Altered Rivers

These dams and associated extractive uses of water have altered two-thirds of the world’s major rivers. And around the globe, government officials, development agencies, and industry leaders are proposing and building new dams to meet growing human demands. In fact, nearly 950 new dams are planned or under construction in South America, and in China, nearly 50 in the Yangtze River basin alone.

Dams and other structures that alter a river's natural course block the pathways used by migrating fish, reduce and rearrange the patterns of flowing water that have choreographed aquatic life cycles for millennia, and change water quality. These changes can have significant effects on the social fabric and economic well-being of people and communities, particularly among those whose livelihoods are closely connected to nature.

As the health of the world’s freshwater ecosystems have declined, so too have their ability to support the needs of both nature and people.

Engaging Decision-Makers to Minimize Impacts

The Nature Conservancy does not advocate the building of dams or other large water-related infrastructure projects. However, we recognize that despite the threats they pose to natural systems, more dams and diversions will be built to meet humanity’s needs.

Because this development poses significant risks to the world’s freshwater ecosystems, the Conservancy believes that it is important to engage with decision-makers in an effort to minimize the environmental and social threats posed by these projects. Working together, we can help ensure that new dams and other structures that alter a river’s natural flow are located, built and operated in ways that promote a sustainable future for freshwater ecosystems and the people who depend upon those systems.

The Nature Conservancy has an important role to play in helping mitigate some of the threats posed by dams and large water development projects. We seek to:

  • Steer new infrastructure away from places that have the most value for biodiversity and for local communities;
  • Inform government agencies and water managers about how these projects impact ecosystems and communities so that they can better understand the tradeoffs associated with each project; and
  • Provide guidance to decision-makers on new projects to help them design and operate dams in ways that minimize negative environmental impacts.

In short, we seek to work with all relevant stakeholders to find ways in which water can be better managed for nature and people.

Solutions Based on Science

To inform our efforts, we draw from our strategic analysis of global conservation priorities, our broad experience in developing solutions to conservation challenges, and our leadership in river science and water policy.

Each opportunity requires collaborating with technical and political experts and community members, facilitating discussion, and building bridges between ecology and engineering. This work is often technically challenging and politically sensitive. However, we believe that it must be pursued if we are going to have a future with healthy rivers capable of supporting both biodiversity and human needs.

Ultimately, our success as an organization will be measured not by our own deeds but by the actions of others, including dam builders and operators, who integrate ecosystem health considerations into planning and decision making.

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