[RedDevil]

Originally Posted by oil pan 4

I found this after about 20 seconds of searching Google.
Banqiao hydroelectric dam, China 1975

https://www.businessinsider.com/dam-...f-death-2017-2

At least 171,000 killed but it could have been as high as 230,000.
It looks like my 250,000 estimate was really low. 300,000 is likely the low estimate.

So, let's see that.

... From 1951 to 1952, China built the giant hydroelectric dam on the Ruhe River with help from the Soviet Union. But in early August 1975, a unusual typhoon moved into the area and broke records for rainfall upriver, pushing the limits that engineers designed for the dam.

On August 8, 1975, the dam collapsed and sent a wall of water nearly 20 feet (6 meters) high and 7.5 miles wide (12 kilometers) downriver, according to a summary of a chapter in the book “The River Dragon Has Come!” by investigative journalist Dai Qing.

The torrent wrecked other dams along the river and killed an estimated 85,000 people. When accounting for later deaths caused by flood-related disease and famine, however, the toll may actually be closer to 220,000 to 230,000 people.

This devastating outlier pushes the statistical risk of dams dozens of times higher, to 54.7 deaths per 10 TWh – about 46 times more risk than nuclear power. Business Insider contacted the National Hydropower Association for comment on the risk hydroelectric dams pose in the US, but we did not immediately receive a response.

So:
- the dam was hit by an exceptionally big typhoon
- the dam was poorly designed (no overflow safegate, or not enough)
- the major cause of death was disease and famine after the event.

This was an outlier event that could and should have been prevented by better design, and the majority of death could have been prevented if the victims had been evacuated and been cared for better. Unfortunately, 1975 was not a good time to be in Communist China.
It says nothing about the safety of hydroelectric power from smaller and properly designed and maintained dams.

If you look at US data only, hydroelectric is the safest power only second to nuclear.