One was the Kyshtym explosion in 1957, I think it was, in the Soviet Union. If I'm not familiar with -- I mean, there are certainly -- and also, in that region, there was systematic dumping of radioactive waste into the watershed there, into a particular lake.

It wasn't systematic, it was a catastrophic accident much like Fukushima.

Kyshtym seems to have been the second worst nuclear accident ever (so far), as measured by the amount of radiation released. The radiation levels on the shores of Lake Chelyabinsk are still so high (fifty years later) that in places you can get a lethal dose of radiation in less than an hour.

http://en.wikipedia.org/wiki/Kyshtym_disaster

This point is rather telling:

the CIA knew of the 1957 Mayak accident all along, but kept it secret to prevent adverse consequences for the fledgling American nuclear industry.