“Round-the-clock monitoring by a network of zonal laboratories and a central laboratory ensures water quality. In Delhi, where people are very vocal, we cannot afford to be lax even for a moment,” claims a dwssdu spokesperson. However, Delhi itself is the Yamuna’s biggest polluter. “The stretch in the vicinity of Delhi (between Delhi and the Chambal confluence) is highly degraded and not fit for any designated use,” says the cpcb’s 1996 Report on Water Quality Monitoring of Yamuna River.

Yamuna enters Delhi at Palla village 15 km upstream of Wazirabad barrage, which acts as a reservoir for Delhi. Delhi generates 1,900 million litre per day (mld) of sewage, against an installed wastewater treatment capacity of 1,270 mld. Thus, 630 mld of untreated and a significant amount of partially treated sewage enter the river every day.

The Wazirabad barrage lets out very little water into the river. In summer months especially, the only flow downstream of Wazirabad is of industrial and sewage effluents. Lesser discharge means lesser river flow and thus, greater levels of pollution.

Water treatment plants have been known to face the prospect of closure due to high pollution loads in the raw water. Risk Assessment of the Yamuna River , the report of an Indo-Dutch government project on water quality monitoring stations that was released in