[scythe]

There have been two hydroelectric power plant failures in the United States in the last fifty years, and one near miss. This is among hundreds of dams many of which have operated for more than a century.

A pumped-storage dam also doesn't increase the area subject to flooding. If the upper dam fails, it flows into the lower lake. This can potentially be a design consideration. It's not like a greenfield hydropower dam.

If you want to play the rare catastrophic risk card, battery fires can release highly toxic hydrogen fluoride. But the damage of climate change is far greater than the very small risk from either dams or batteries, which is preventable in both cases with proper maintenance and monitoring. I think the tail risk question is moot, honestly.

[XorNot]

There have been considerably more dam failures though: https://en.wikipedia.org/wiki/Category:Dam_failures_in_the_U...

Which is the point: any retained body of water like this is a significant geotechnical engineering project.