In 1990, being close to the shore of lake Karachay would give you a lethal radiation dose in a matter of minutes.
The lake was polluted from the Mayak Production Association, the largest nuclear reactor in the Soviet Union, which was built secretly in the late 1940s. Lake Kyzyltash was the largest and closest source of cooling water, which was essential for cooling the reactors. However, it was also used to dispose radioactive waste. Lake Karachay, was also used as rubbish bin for hazardous waste. The Russian- Soviet government kept Mayak entirely secret until 1990. According to reports, there was a 21 percent increase in cancer incidence, a 25 percent increase in birth defects, and a 41 percent increase in leukemia in the surrounding region of Chelyabinsk. The Techa river, was also contaminated resulting in an epidemic local radiation illness. Lake Karachay is now full of concrete, however underground water contamination in the past or even now remains a possible nightmare scenario, as the hazardous waste has only been covered not eliminated.
The radiation emitted from Lake Karachay was extremely strong, even stronger than Chernobyl, especially in terms of density from unit mass. An hour being close to the shore would give a radiation of 600R to a human, enough to kill him. Raising global awareness in terms of the dangers of nuclear facilities (especially in the wrong hands) is vital. The intelligence of those who discovered the theoretical scientific foundations of atomic energy release, or even the pioneers of technology of nuclear reactor technology does not mean that those who will use it will have an equal level of mental awareness.