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The Snail Darter Is Safe | Earth Wise

November 14, 2022 By EarthWise Leave a Comment

The snail darter is a three-inch-long snail-eating fish that was once only found in the Little Tennessee River. When that river was going to be dammed by the Tellico Dam under construction in the 1970s, the snail darter was listed on the endangered species list and the little fish subsequently became the subject of a legal battle that made it all the way up to the U.S. Supreme Court. With the dam project 95% complete in 1978, the Supreme Court blocked further construction, citing the Endangered Species Act. A year later, Congress exempted the project from the requirements of the Act, thereby clearing the way for the completion of the dam.

In order to save the snail darter, biologists transplanted the fish into several other nearby rivers and waterways. In addition, the Tennessee Valley Authority modified the operation of the Tellico Dam to release more oxygen-rich water downstream. Beyond those measures, the river cleanup under the Clean Water Act further aided the fish’s recovery.

In 1984, the snail darter was removed from the endangered species list and was listed as threatened or vulnerable. Recently, the U.S. Department of the Interior officially removed the snail darter from the federal list of threatened and endangered wildlife.

The snail darter is the fifth fish species to be delisted because its population has recovered. It is the first in the eastern United States. With better management of water releases at dams, many other imperiled aquatic species could be recovered.

Overall, more than 50 plants and animals have recovered under federal protection, including American alligators, humpback whales, peregrine falcons, and bald eagles.

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Once at Center of Controversial Case, the Snail Darter Fish Is No Longer Threatened

Photo, posted July 22, 2015, courtesy of The U.S. Fish and Wildlife Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

More Dam Failures Likely | Earth Wise

June 24, 2020 By EarthWise Leave a Comment

Two dams in Central Michigan were breached by rain-swollen floodwaters in May and forced the evacuation of tens of thousands of residents and prompted officials to warn of life-threatening danger from a flooded chemical complex and a toxic waste cleanup site. Engineers say that most dams in the U.S. were designed many decades ago – in some cases, a century ago – and are not suited to a warming world with ever stronger storms.

The dams in Michigan gave way for the same reason behind most dam failures: they were overwhelmed by water, in this case by five inches of rain falling over two days after earlier storms had saturated the ground and swollen rivers.

It can’t be proven whether this specific set of events was triggered by climate change, but global warming is definitely causing some regions to become wetter and is increasing the frequency of extreme storms. And these trends are expected to continue as the world continues to warm.

All of this puts more of the 91,500 dams in the U.S. at greater risk of failing. The American Society of Civil Engineers, in its latest report card on infrastructure issued in 2017, gave the nation’s dams a “D” grade.

Historically, dams have been designed based on past weather history to predict the magnitude of the maximum potential flood that a dam would have to withstand. There was no expectation that future weather patterns might be very different. Infrastructure designers will clearly need to change their practices.

For existing dams, operational changes might be called for, such as reducing water levels in anticipation of more extreme storms. Upgrades might include changing spillway designs to accommodate larger water volumes over a longer time period.

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‘Expect More’: Climate Change Raises Risk of Dam Failures

Photo courtesy of Eye in the Sky/Youtube.

Earth Wise is a production of WAMC Northeast Public Radio.

Concerns About Dam Safety

August 22, 2019 By EarthWise Leave a Comment

The United States has a total of 91,000 dams of various sizes and types. Many of them are aging and sorely in need of repairs. All that maintenance would add up to tens of billions of dollars. Experts are increasingly worried that as extreme precipitation events become increasingly common, dams are increasingly at risk of failure, threatening lives and posing environmental risks.

In 2017, Oroville Dam in California – the tallest dam in the country – nearly collapsed. That incident forced the evacuation of 190,000 people and cost the state of California $1.1 billion in repairs. California is considered one of the nation’s leading states in dam safety management and yet the partial disintegration of Oroville’s two spillways during a heavy rainstorm was not anticipated.

So far, federal and state dam safety officials have not been able to get disinterested state legislatures and the U.S. Congress to fork up the money needed for repairs to the nation’s aging dam infrastructure.

Th American Society of Civil Engineers gave the nation’s dams a D grade on the latest infrastructure report card. They estimate that the cost of rehabilitating dams whose failure would threaten human life at nearly $45 billion, and the cost of fixing all dams in need of repair at more than $64 billion.

Scientists say the likelihood of dam failures – which not only threaten lives but also release toxic sediments trapped in reservoirs behind many dams – will increase as extreme precipitation events become more frequent in a warming world. Apart from about 1,500 dams owned by federal agencies, regulating dam safety is primarily the responsibility of the states. So far, states have not applied remotely sufficient resources to a growing problem.

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