Q. I've heard that hydropower has a negative impact on biodiversity. Is that true? How so? - Aidan, MI


A. Water is one of the most powerful substances on earth. The stuff covers over 70% of the earth’s surface, and is essential to the survival of all living things. What’s more, it fulfills the electricity, heating, and cooling needs of millions of people around the world. In the U.S., hydropower supplies around 70% of the country’s renewable energy—that’s more than what’s provided by wind, solar, and geothermal power combined.

But any source of power, however renewable, can sometimes have negative impacts on the environment, and hydropower is no exception. When a hydropower dam is constructed, it blocks a flowing river and essentially turns it into a stagnant lake, and in many cases, fish are no longer able to follow their usual path. Some salmon and other fish populations have been decimated—and several even classified as endangered—as a result of dam construction.

Flooding is another problem that can come hand in hand with dam construction. Take the Three Gorges Dam in China—the largest hydropower facility in the world. It’s already displaced millions of people, and will certainly displace more in the future. The Three Gorges Dam has drowned thriving wetlands, home to countless plant and animal species, and has ruined archeological sites. This is an extreme case, but lots of other hydroelectric dams cause the same kinds of destruction on a smaller scale. Many in South America, for example, flood and degrade rainforests. 

Luckily, some of the damage done to biodiversity by hydropower can be reduced by equipment upgrades, mitigation measures, and proper management. Developers can also turn their attention to other types of hydropower facilities that don’t rely on dams. “Run-of-the-river” systems—facilities that generate power from naturally flowing bodies of water—are one lower-impact way to capitalize on hydropower. Other smaller-footprint options include wave, tidal, and hydrokinetic power. For more info on these different ways to produce renewable energy, check out the National Hydropower Association.

If you’re interested in the impact of a particular hydropower facility near you, look it up on the Low Impact Hydropower Institute's website. LIHI is a non-profit organization dedicated to reducing the impacts of hydropower generation.

Story by Alyssa Kagel. This article originally appeared in Plenty in July 2008.

Copyright Environ Press 2008

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