A green film that resembled an oil slick covered the soupy, near-still waters of the Periyar river some half a kilometre downstream of the Pathalam regulator-cum-bridge around twilight hours on Friday.
“It didn’t mix with water and covered the hull of the canoe like an oil film as we went to have a look. It appeared around nightfall and lingered thereafter,” said V.B. Maheshkumar, a local resident. Officials of the Pollution Control Board collected samples of the water. PCB sources said the slick looked like algael bloom and some upflow in the river was noticed. “But, whether it was algael bloom or industrial discharge will only be known upon testing the sample collected,” said an official.