A thick layer of toxic white froth has covered stretches of the Yamuna near Kalindi Kunj as falling temperatures and churning water intensify foaming ahead of the Chhath festival.
Surfactant molecules from untreated domestic sewage, industrial waste, and decomposing water hyacinth combine at the Okhla barrage to create stable winter froth.
The Delhi Jal Board will spray chemical defoaming agents in coming weeks, having used 48,000 kilograms of chemicals over 63 days last year.