18 months ago. You do remember the weeks of non-stop media coverage, right?
Not a major disaster, of course. Nothing can compare with the Banqiao Dam failure in China, which killed 26,000 people in 1975.
Of course, communist countries were notoriously careless about safety and the environment. In Western countries, Hydro power is perfectly safe...
39 Dead in Georgia USA, 1977 from a decommissioned hydro plant. Just because it's not in use any more, doesn't mean it's not still dangerous.
And, of course, the only one of these I actually heard of without looking for it, the 2000 killed in Italy in 1963. Hydro plants are particularly vulnerable to earthquakes.
This isn't meant to be an anti-hydro rant. Hydroelectric power is the only proved form of renewable energy. But all power stations of any kind, by their essential nature, concentrate large quantities of energy into a small volume. That is intrinsically dangerous, whether its lakes of dammed water, radioisotopes, oil or natural gas... The concentration of energy almost always has environmental impact, and always has risk.
No conceivable nuclear accident matches Banqiao dam. No nuclear accident in the first world has matched Kelly Barnes Dam (unless something new goes seriously and unexpectedly wrong at Fukushima). Arguably, no nuclear accident in history has matched Sushenskaya — and that wasn't even kept secret, it just wasn't newsworthy.