MOSCOW — The pictures seem to show a little piece of paradise in Siberia: a beautiful expanse of turquoise water, inflatable beach toys and women lounging in bathing suits.

The site, a lake in Siberia, has become such a draw this summer for people posting on Instagram that whole social media pages are dedicated to its charms.

There is only one problem: The lake is a man-made waste site for a power plant, Heating and Electrical Station Number 5. And that irresistible blue hue is not the color of pristine waters reflecting off the sky, but rather the deposits of calcium salts and metal oxides, according to the electrical company that runs the plant.

Nevertheless, people have flocked to the site for photographs of an imagined tropical bliss outside Novosibirsk, a sprawling industrial city in Siberia with a population of 1.6 million people, better known for its frigid winters and metallurgical factories than its beaches.