Altered Rivers

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.

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.

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.

Tools and Resources

The Nature Conservancy works with partners to develop tools and provide science and resources to help freshwater practitioners and policy makers:

-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,

 -Provide guidance to decision-makers on new projects to help them design and operate dams in ways that minimize negative environmental impacts.

Tools and Resources

Technologies including the Indicators of Hydrologic Alteration (IHA) software, flow restoration database and the Regime Prescription Tool (RPT) to aide freshwater practitioners can be found by clicking here.

Journal Articles about Freshwater Conservation

Suggested articles for Reducing the Ecological Impacts of Dams:

Richter, B.D., Warner, Andrew T., Meyer, Judy L., and Lutz, Kim. 2006. A Collaborative and Adaptive Process for Developing Environmental Flow Recommendations.  (.pdf, 558 kb)

Richter, B.D., Roos-Collins, R, and Fahlund, A.C. A Framework for Ecologically Sustainable Water Management. Hydro Review, August 2005 © HCI Publications (.pdf 261kb)

Baron, J.S., N.L. Poff, P.L. Angermeier, C.N. Dahm, P.H. Gleick, N.G. Hairston, R.B. Jackson, C.A. Johnston, B.D. Richter, and A.D. Steinman. 2002. Meeting ecological and societal needs for freshwater. Ecological Applications 12:1247-1260.
View the paper (.pdf, 196 kb)
(This paper is posted with the permission of the Ecological Society of America.)

Please contact Diedre Paterno Pai: dpaterno-pai@tnc.org with any questions, comments or suggestions