The sole water source for Delhi’s burgeoning population is fast losing ground, with environmentalists describing the Yamuna as a “dead river”. Here is a ‘postmortem’ on what caused the ‘death’

* The Yamuna’s 22-km stretch in Delhi is barely 2 per cent of the length of the river, but contributes over 70 per cent of the pollution load.

* Pollution levels in the Yamuna have risen. Biochemical oxygen demand (BOD) load has increased by 2.5 times between 1980 and 2005 - from 117 tonnes per day (TPD) in 1980 to 276 TPD in 2005.

* Delhi discharges about 3,684 MLD (million litres per day) of sewage into the Yamuna.

* The faecal coliform count, which indicates the presence of disease causing micro-organisms, is nearly 25,000 times more than the limit prescribed for bathing.

* Delhi and Agra together account for 90 per cent of the pollution in the river.

* The Capital has 16 drains discharging treated and untreated wastewater/sewage into Yamuna.

* Approximately 1,900 MLD of waste water is discharged from the municipal sector and 320 MLD from the industrial sector. The installed capacity for treatment is 1,270 MLD.

* The Najafgarh drain contributes to 60 per cent of the total wastewater and 45 per cent of the total BOD load being discharged from Delhi into the Yamuna. The municipal wastewater has increased from 960 MLD in 1977 to 1,900 MLD in 1997.

* The capacity for treatment has been increased from 450 MLD in 1977 to 1,270 MLD in 1997.

* A Central Pollution Control Board study on river water quality at the upstream of Wazirabad shows dissolved oxygen (DO) level at 7.5 mg/l and BOD level at 2.3 mg/l.

* At downstream Okhla, the DO level declined to 1.3 mg/l with the BOD at 16 mg/l, indicating considerable deterioration in water quality due to discharge of sewage and industrial effluents.

* The coliform count at Wazirabad is 8,506/100 ml whereas at Okhla, it increases to 3,29,312/100 ml, as against the prescribed standard of 500/100 ml.