Yamuna's dissolved oxygen (DO) level, that supports aquatic life, has plummeted to zero at different points in the river's journey through the national capital, a Delhi Pollution Control Committee study has found.
The recent idol immersions aggravated its already alarmingly high pollution level, shooting up Biochemical Oxygen Demand (BOD), that indicates the level of organic pollution, the report says.
According to DPCC, a waterbody has to have a minimum 4 mg/l of DO while BOD should not exceed 3 mg/l for aquatic life to thrive.
However the study, commissioned to find the water quality of Yamuna on the occasion of Dussehra, has found that BOD shot up to as high as 38 mg/l at Kudesia ghat during immersions, where DO was zero.
DO was found to be zero across Yamuna ghats on October 11. Only at Shyam ghat it had a 2.1 mg/l presence, down from 6.1 mg/l the previous day.
At Shyam ghat, Geeta Ghat, Mayur Vihar's Chhath ghat, Haathi ghat and Kalindi ghat, BOD was recorded at 12, 25, 19, 33, 28 mg/l respectively on October 11. The respective levels on October 9 were 8, 20, 13, 24 and 20 mg/l.
In a 2015 report, Central Pollution Control Board had identified unabated discharges of wastewater, predominantly from domestic sources, into Yamuna responsible for its deteriorating water quality, especially in its stretch after Wazirabad barrage.
"The other reason is the non-availability of fresh water in the river after Wazirabad barrage especially during non- monsoon period, which is essential to maintain self- purification capacity of the river," it said.
Based on the discharge and BOD load of 18 drains that join Yamuna in Delhi, Najafgarh drain was found to be the biggest polluter, followed by the Shahadara drain.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)