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Jeff Opperman is The Nature Conservancy's senior advisor for sustainable hydropower. He works to promote ecologically sustainable water management in river basins with hydropower infrastructure. Through this work, Jeff has provided strategic and scientific assistance to environmental flow assessments for several rivers in the United States and for the Yangtze River and the Patuca River (Honduras). Get Involved Join the Conservancy's online community and you can explore new places, receive email you want and build your own personalized nature page! "Truly sustainable hydropower can only be evaluated and designed across large geographic areas, such as a major river basin or region." —Jeff Opperman, The Nature Conservancy's senior advisor for sustainable hydropower How We Protect Watersheds Explore a cool interactive feature to see how the Conservancy protects freshwater resources worldwide. Dams Around the World Watch a slideshow on how the number of dams has increased around the world since 1750. Go Deeper Dams and Freshwater Conservation Find out how the Conservancy works around the world to minimize the environmental and social impacts of dams. The Turbine Beneath Our Feet Read this Big Idea about how using existing water transport systems could help generate even more energy. Minimizing Dam Impact on the Yangtze See how the Conservancy is helping reduce the environmental impacts of twelve new dams planned for China's upper Yangtze River.

By Jeff Opperman

River ecosystems support a wide range of unique animal and plant species — and healthy rivers can provide immense benefits to communities, including food production and clean drinking water. But rivers are among the most threatened of the world's ecosystems, as they've lost proportionally more of their species and habitat than either land or ocean ecosystems.

One of the primary reasons for these losses — and for future threats — is the construction of dams to store water for drinking, irrigation, flood control and hydropower. Dams block the movement of fish and other creatures and can also greatly change a river's flow patterns — the rise and fall of water that orchestrates nearly all aspects of river life.

Two-thirds of the world's rivers have already been significantly altered by dams — and, in part due to growing concerns about climate change, thousands of new hydropower dams are being planned and built around the planet.

This rapid expansion of hydropower poses a thorny environmental challenge: Although hydropower is generally a low-carbon source of energy, it cannot be considered "sustainable" unless it can minimize the loss of freshwater biodiversity and the disruption of the way of life of communities that depend on free-flowing rivers.

Avoiding 'Death by a Thousand Cuts'

The Nature Conservancy has waded right into the middle of this challenge.

For years, Conservancy scientists and policy specialists have been developing tools and methods to improve how dams are operated throughout the world, and we've collaborated with engineers in the United States, Asia, Africa and Latin America to minimize impacts and maintain more natural river flows below hydropower dams.

But because the scale of the threat has grown, so too must the scale of our strategy. We now focus our efforts on a central principle: Truly sustainable hydropower can only be evaluated and designed across large geographic areas, such as a major river basin or region.

To put it simply, each new dam — no matter how well it is designed and operated — will cause a loss of ecological integrity and function within that particular river. If we try to mitigate these impacts dam-by-dam, entire river basins or regions will eventually die a "death by a thousand cuts."

But if instead we plan for dam development across large river basins, we will be better able to direct dam-building to the least-damaging places within the basin, and ensure that key ecological processes — such as the flow of water, sediments, and nutrients — are sustained within the river basin as a whole.

River Basins Can Provide Energy and Healthy Ecosystems

To be effective, we know we must work at the earliest possible stage of planning for hydropower development, integrating and optimizing objectives for both energy and conservation.

Only by engaging at this stage can we hope to influence where dams go and where they don't go. Only here can we move the environmental mitigation requirements of dams away from piecemeal — and often ineffective — measures and toward the creation of integrated, functioning freshwater protected areas.

The Nature Conservancy is currently pursuing this integrated planning strategy in Colombia, Central America, the Yangtze River in China and the Zambezi River in southern Africa. We are finding a receptive ear for this strategy among government agencies, and the funders and builders of large dam projects. They recognize that this approach will lead to dam projects with greater certainty and lower controversy — precisely because they emerge from a planning process focused on true sustainability.

The world faces immense challenges in our efforts to conserve the planet's rivers. Our prospects for success depend on developing solutions that equal the scope and breadth of the challenge.

(March 2009)

Photo credits (top to bottom, left to right): © Discussing dam construction plans for the Yangtze River (Brian Richter/TNC); courtesy of Jeff Opperman