India, Oct. 27 -- Accumulated sludge on the Yamuna riverbed and polluted water from drains upstream are contributing to frequent spikes in ammonia levels in the river, which often lead to disruption in Delhi's water supply, the Central Pollution Control Board (CPCB) has found.

Even the relatively cleaner stretch of the Yamuna between Palla and Wazirabad in Delhi has had deteriorating water quality, with the CPCB identifying sludge accumulation and nitrogen-rich wastewater entering the river as key factors behind the recurring problem.

In a report submitted to the Upper Yamuna River Board (UYRB), the CPCB said the water holding pondage area from which the Wazirabad and Chandrawal water treatment plant draws raw water could be generating ...