Delhi, The biggest culprit
“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 inJanuary 1996, notes that the Haiderpur water intake had, at an average, to be closed five times a year. “These ‘accidents’ were mainly related to flushing of drains and canals upstream of Delhi, without appropriate communication between the concerned authorities,” says the report. However, dwssdu authorities maintain that they would get to know any change in the pollution load on wyc six hours before it reached Haiderpur, as water is monitored upstream. In February 1996, the Wazirabad treatment plant had to down its shutters for eight hours on a day when the organic pollution load of the raw water was unusually high. In surface water, do level has to be at least four mg/l to make it fit for use after treatment; at Wazirabad, the do level was nil. This depletion was caused by effluents from breweries in Panipat.
From the Okhla barrage, which is the exit point for the river in Delhi, the Agra canal branches out from Yamuna. During the dry months, almost no water is released from this barrage to downstream Yamuna. Instead, discharges from the Shahadara drain join the river downstream of the barrage, bringing effluents from east Delhi and noida into the river. This is the second largest polluter of the river after the Najafgarh drain.
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