It might look pretty, but this lake in India is anything but. What you’re seeing above is water rich in ammonia and phosphate, and low in oxygen, forming an extremely toxic froth. In fact, it’s so toxic that it occasionally catches on fire due to the oil, grease, and detergents that are in it.

The froth forms on the 36-kilometer-wide (22-mile-wide) Bellandur Lake in Bangalore, and is then carried by a canal. The foam is believed to be the result of pollutants being dumped in the lake for decades, and when it rains, it spills out onto surrounding roads and areas. It smells pretty bad, too, apparently.

The video above shows parts of the lake catching on fire. NDTV/YouTube.

Only small parts of the foam actually catch fire, although it’s not clear how it begins. Chemical reactions could be causing the foam to combust, while the fire could be due to methane building up on the surface of the water. But experts have said just a cigarette thrown in the lake would be enough to ignite it.

Winds also pick up the foam and send it across the nearby city, causing a significant problem. The exact health hazards are not known – but considering it originated from a mixture of water, chemicals, and sewage, it’s probably not good.

Petitions as far back as 2000 have tried to get authorities to do something about the problem, but to no avail. In June, the LA Times said Bangalore was "choking from illegal construction, unregulated dumping, official mismanagement and mounting waste."

A similarly polluted river in the U.S. in the 1960s, the Cuyahoga River in Cleveland, Ohio, is often credited with starting the American environmental movement. Maybe the same, too, will be true for India.

This video shows how easily the foam can be blown around. Sanjith Shetty/YouTube.