India, Aug. 12 -- Accumulated sludge in the Yamuna bed at Wazirabad may be contributing to ammonia spikes that have caused recent disruptions in Delhi's water supply, preliminary findings of a Central Pollution Control Board (CPCB) study based on samples collected from the pondage area have shown, government officials said.

The concern comes as even the relatively cleaner stretch of the Yamuna between Palla and Wazirabad has recorded deterioration in key water-quality parameters, according to monthly reports of the Delhi Pollution Control Committee.

The CPCB collected samples from the Wazirabad pondage area during a period of high ammonia levels, and its preliminary findings suggest that accumulated sludge may be one of the factors behi...