New Delhi, Aug. 12 -- Accumulated sludge in the Yamuna bed at Wazirabad may be contributing to ammonia spikes that have caused disruptions in Delhi's water supply, preliminary findings of a Central Pollution Control Board (CPCB) study have shown, officials said. Even the cleaner stretch of the Yamuna between Palla and Wazirabad has recorded deterioration in water-quality parameters, according to monthly Delhi Pollution Control Committee reports. The CPCB collected samples from Wazirabad during high ammonia levels. Preliminary findings suggest that accumulated sludge may be one of the factors behind elevated ammonia levels in raw water, officials said. The study was undertaken at the behest of the Upper Yamuna River Board (UYRB), which is ex...