Thin Layer Of Toxic Foam Floats Again In Delhi's Yamuna River Thin Layer Of Toxic Foam Floats Again In Delhi's Yamuna River Environmentalists earlier have stated that the reason for the frothing could be the release of certain gases when reacting with few specific bacteria. The toxic foam was seen floating in the Yamuna river on April 26 also. New Delhi: A thin layer of toxic foam was seen floating in the Yamuna river at Delhi's Kalindi Kunj area today. The toxic foam was seen floating in the Yamuna river on April 26 also. Environmentalists earlier have stated that the reason for the frothing could be the release of certain gases when reacting with few specific bacteria.