Hydropower is hurting wildlife

Hydropower is hurting wildlife
© Thinkstock/Istock/Sekarb

The wealth of biodiversity and other ecological benefits that rivers provide have fueled human progress for thousands of years. But progress has come at a cost. According to a new study published in the scientific journal Nature, infrastructure development and other man-made changes have fragmented or disrupted two-thirds of Earth’s longest rivers. In the study, researchers from McGill University, World Wildlife Fund and other institutions found that dams are the leading cause of this loss of river connectivity.

Today, there are roughly 60,000 large dams around the world, with over 3,700 more hydropower dams currently planned or under construction. And while hydropower has a role to play in the world’s transition to clean energy, its impact on river connectivity can make it a double-edged sword for the environment. 

The rapid loss of free-flowing rivers has serious implications for both nature and people. First, dams fragment aquatic habitats and block fish migration. Populations of freshwater species have already experienced a staggering 83 percent decline since 1970. More dams will likely further deplete their numbers, impacting tens of millions of people whose food and livelihoods depend on freshwater fish harvests.


Second, dams trap sediment and nutrients, keeping them from traveling downriver to fertile deltas that are home to 500 million people. Sediment supply build up deltas is critical in an era of rising sea levels, while nutrients ensure that deltas remain among the most productive agricultural regions in the world.

Climate change can also undermine the economic case for dams, as extreme droughts or floods challenge their ability to generate energy and increase the risk of failure. Many nations would benefit from considering alternatives to hydropower like solar and wind, which not only have a smaller environmental footprint but also are becoming less expensive in many places. Costs for solar and wind have dropped significantly and will continue to do so. The price of solar is projected to fall another 25 percent over the next 5 years, while offshore wind is projected to fall another 40 percent.

The private sector has taken notice, in the U.S. and around the world. Between 2016 and 2026, solar photovoltaic installers and wind turbine technicians are projected to be among the fastest growing American jobs. And global investment in solar and wind now far exceeds investment in hydropower.

Large dams, on the other hand, have been shown to often run over budget, exceed their original construction schedules and come with an increasing risk of failures as they age. They often displace thousands of people, disrupt the social fabric and result in social conflict and protests. The vast sums of money associated with these projects can also encourage corruption and have contributed to debt crises in a number of countries.

Aging infrastructure and inordinate costs are driving a wave of dam removals in some parts of the world. In the last two decades, for example, the U.S. has removed more than 1,500 dams. In many of these places — such as the Elwha River in Washington State — nature has come roaring back.


The U.S. has made some promising investments in helping countries develop climate-smart energy solutions. For example, through USAID’s clean energy and biodiversity conservation programs, the U.S. partners with developing countries to achieve these dual goals, both of which contribute to international security and economic prosperity.

We also have mechanisms that we can better use to promote and finance solar and wind projects. Private-public partnerships like the Power Africa initiative, which aims to help African nations double their electricity access, could focus more on solar and wind projects. Development agencies like the Millennium Challenge Corporation (MCC) and the new U.S. Development Finance Corporation (DFC) could work with nations to scale up wind and solar rather than business-as-usual hydro or fossil fuels.

Governments are seeking ways to address climate change and meet the water, food and energy demands of their growing populations. But they don’t have to choose between fighting climate change and conserving free-flowing rivers. While hydropower may be the right choice in some scenarios, the increasing cost-effectiveness of solar and wind offers viable alternatives. As nations grapple with these choices, the U.S can help them implement solutions that are good for their communities, their rivers and the planet.

Michele Thieme is lead freshwater scientist at World Wildlife Fund. Follow her on Twitter at @MicheleThieme.