The sources look good [1] In particular, the deaths as a result of hydroelectric power caught some catastrophic failures. Dams are very, very dangerous constructions, and have a failure mode that makes a nuclear plant look safe by comparison. Just one major Hydroelectric Dam [2], Bangiao, was responsible for on the order of 50,000 deaths related directly to the Dam Failure.
[1] http://nextbigfuture.com/2011/03/deaths-per-twh-by-energy-so...
[2] http://en.wikipedia.org/wiki/Banqiao_Dam