Hydro has a pretty terrible track record with regard to safety, most of it because of a single accident: the Banqiao Reservoir Dam failure, which caused 230000 deaths. And even if much less dramatic, dam failure still happen regularly, costing deaths, property and environmental damage.

And while I tend to think of hydro as the ideal energy source (renewable, on demand, with built-in storage), safety is not one of its strong points. Or at least, not with the way it is managed now.