After an explosion of interest on social media, the company said it had been forced to warn potential visitors that "walking along the ash dump is like walking on a military firing range: risky and undesirable".
After realising their ash dump had become the "star of social networks", they chose to answer some of the commonly asked questions.
The calm turquoise waters are a magnet for Instagrammers desperate to take the flawless selfie. There's just one small problem: It's not a pristine wilderness, but a man-made toxic waste dump.
They added that the bottom of the pond is apparently very muddy, which could make it hard for swimmers to escape.
The lengthy advisory, however, appears to have done little to quell the flow of visitors, marking the latest example of the lengths to which people will go for the flawless Instagram photo.More news: Karnataka political crisis | Trinamool organises Opposition protest in Parliament
Thanks to its social media star status, the lake even has its own Instagram account: @maldives_nsk.
A post claimed that so many tourists had started visiting the site that thieves had started breaking into cars while visitors took photos.
Like Zheleznova, most people respected the warnings, choosing to take their pictures on shore.
But even such a strongly worded warning doesn't seem to be deterring those seeking a great photo op. Here's one guy's report, courtesy of an Instagram caption: "The next morning, my legs were slightly red and itchy day two, then it went [away]". "The water tastes a bit sour, looks like chalk".
"Naturally, you should not swim there, but because of a photo shoot lasting an hour you will not grow a third hand", she wrote.More news: 'Shaken To My Core': Testimony Describes Conditions For Detained Migrants
The pond is a dumping site for coal ash mixed with water, according to the Siberian Generating Company (SGK).
"The dump is NOT poisonous: blue gulls do not fly there, and plants do not die". The lake was created in the 1970s and is the largest of its kind in Siberia.
It is not a lake at all, merely the result of calcium salts and other metal oxides from the nearby thermal power station, which provides energy to the city of Novosibirsk. "Skin contact with such water may cause an allergic reaction!"
"This didn't stop some Russians to organise whole picnics by the lake".More news: People and animals evacuated as raging fire burns 3,000 acres in Maui