Have we learned nothing from the Venezuelan power blackout from 2-years ago?

You don't need to blow up a hydroelectric dam to cause tons of problems. Computers control the rotational speed of the turbines. There are braking mechanisms that regulate the speed and water flow rates.

A good computer virus that allows the turbines to free-wheel... does wonders. All the bearings come apart, the equipment can't handle the generated forces... and parts start flying. :>)

It's all good fun.