There Are About 91,500 Large Dams In The US: More Will Fail As Weather Grows More Extreme

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What’s left of the Sanford Lake Dam and spillway on Thursday on the Tittabawassee River in Michigan.Credit...Tannen Maury/EPA, via Shutterstock

The dam that failed in Central Michigan on Tuesday gave way for the same reason most do: It was overwhelmed by water. Almost five inches of rain fell in the area in the previous two days, after earlier storms had saturated the ground and swollen the Tittabawassee River, which the dam held back. No one can say yet whether the intense rainfall that preceded this disaster was made worse by climate change. But global warming is already causing some regions to become wetter, and increasing the frequency of extreme storms, according to the latest National Climate Assessment. The trends are expected to continue as the world gets even warmer.

That puts more of the nation’s 91,500 dams at risk of failing, engineers and dam safety experts said. “We should expect more of these down the road,” said Amir AghaKouchak, a professor of civil engineering at the University of California, Irvine. “It’s unfortunate but this is what the trend is going to be.”

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Rivers and reservoirs swollen by rainfall are the cause of most of the failures. “It’s not a new thing per se,” Mr. McCann said. But some recent dam episodes have been shown to have a climate change link. In February 2017, at Oroville Dam in California, the tallest in the nation, heavy mountain runoff into the reservoir led to the near-failure of an emergency spillway and severe damage to the main spillway. Nearly 200,000 people were evacuated as a precaution and repairs cost more than $1 billion.

A later study found that human-caused warming had increased early season runoff in the Sierra Nevada, contributing to the high water levels at the dam. And there is little doubt that extreme rainfall events are getting more frequent. The fourth National Climate Assessment, issued in 2018, showed that the number of heavy precipitation two-day events has increased in all regions except the Southwest since the early 1900s. And since 1950, extreme events increased by more than 50 percent in the Midwest.

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https://www.nytimes.com/2020/05/21/climate/dam-failure-michigan-climate-change.html

[SWBTATTReg]

1. A lot of these dams are old, part of the 'infrastructure' repairs that need to be done in this ...

Country. Bridges too.

[2naSalit]

2. And at least 40 years overdue. ...nt

[SWBTATTReg]

3. Really. I know about this issue because Missouri (where I live) has a rather unbeiveble

number of bridges (6,000), I guess we do indeed have a lot of rivers, lakes, creeks, etc. They keep harping about an infrastructure bill in Congress but nothing seems to get done on it. I guess they can't decide how to pay for it. Maybe not spend trillions of dollars in arms/military over 5 years and use it instead to pay for new bridges, roads, dams, etc.?

[2naSalit]

4. If we cut the military budget in half...

we could feed everyone, build and fund enough schools for everyone and repair our infrastructure that should be retained and build new green infrastructure too.

[SWBTATTReg]

5. Exactly!