Environmental experts say levels of contamination were 193 times normal.
Locals warned not to use water for baths as authorities urgently check for radioactive or toxic substances.
In fact, the 'rain’ turning all cars red in a Norilsk parking lot is a sign that pollution IS finally being tackled.
Krasnoyarsk's skies have been black since the start of the New Year, with locals complaining of 'chemical smell', lack of oxygen.
Yet nickel capital Norilsk - the city with the highest industrial emissions - does not feature in the top ten.
The Molchanka’s waters have been this strange hue for a week, and now feared pollution threatens drinking supplies in city of Tyumen.
The Russian president's trip on Wednesday coincided with a marked improvement in levels of pollution, they claim.
In beach resort of Listvyanka alone, 98 contaminated streams are disgorging sewage and chemical waste into the pristine waters of the world's oldest lake.