India, March 4 -- Toxic froth and an ammoniacal stench at the Wazirabad barrage, a crucial drinking water source for Delhi, have triggered fresh concerns about pollution levels in the Yamuna, with activists warning that contamination may now be creeping into upstream stretches of the river, once considered relatively cleaner.

Typically, visuals of toxic foam on the river surface are observed downstream at Kalindi Kunj near the Okhla barrage, after 22 major drains add to the pollution load. The water quality at Wazirabad is generally considered relatively better, and the city draws raw water from the Wazirabad pondage area to feed two of its water treatment plants. Activists have expressed concern after recent photographs showed frothing ...