Delhi's Yamuna cleaner: Experts flag discrepancies in DPCC data; pollution concerns persist

NEW DELHI: Water quality data released Sunday by Delhi Pollution Control Committee shows Yamuna was in better health in Nov and Dec 2025 than in the corresponding period of previous year, both in terms of faecal coliform levels and biochemical oxygen demand (BOD).However, some experts and activists pointed to discrepancies suggesting that the data didn’t “add up”. For instance, they said BOD at Kalindi Kunj in Nov-Dec was shown to be better than in Oct, when Yamuna had been cleaned for Chhath, had much better flow and looked visibly cleaner.Yamuna smells — and so do numbersThe DPCC report said faecal coliform level (indicating untreated sewage) was 92,000 MPN/100 ml in Dec and 20,000 units in Nov at the ISBT bridge, right after the Najafgarh drain flows into the river, compared with 8,000 in Oct during Chhath Puja.

The safe limit is 2,500, and the desired level below 500 MPN/100 ml.BOD, which had peaked at 25mg/l in Oct, rose to 33mg/l in Nov, with the peak coming down again to 25mg/l in Dec. This was still eight times the safe limit of 3mg/l. Interestingly, the river was far better than at the same time last year. The faecal coliform peaked at 8.4 million units in Dec 2024 and BOD peaked at 70 mg/l.In Oct 2025, the river was cleaned with an excessive flow of water from the upstream barrage during the festival of Chhath, fixing the problem of frothing and improving overall river health.

However, froth resurfaced by the first week of Nov as the cosmetic management during Chhath faded, and the real, stinking river reappeared.Experts pointed out that pollution levels as compared with Oct did not align. Some areas, like the Okhla Barrage, showed a BOD of 20mg/l in Oct, while in Nov and Dec, when frothing and stench returned due to lower flow, the BOD had improved to 14mg/l and 17mg/l, respectively, at the same spot.The water quality of some drains and their corresponding confluence points also did not add up, they said. TOIsent queries to the nodal officer at DPCC but did not receive a reply.“In Nov and Dec, DPCC’s report says that pollution dropped. At Kalindi Kunj, the BOD in Nov was 14mg/l and 17 mg/l in Dec. Dissolved oxygen (DO) was also over 2mg/l in both months. If we compare this with the sample taken on Oct 20, 2025, when fresh water flow was much higher, the BOD was 20mg/l and DO was 1mg/l.

This raises doubts. How come, when the river was visually clean, the BOD was worse than in the months when frothing and stink returned? Also, if we see the quality analysis of drains, then for Nov and Dec, around six to seven drains had BOD levels over 100g/l, yet the river quality showed signs of improvement at certain stretches,” said Pankaj Kumar from Lone Earth Warrior.He also pointed out that the BOD at ISBT bridge for Nov and Dec was 24 mg/l — a slight deterioration since Oct when it was 22 mg/l — as the Najafgarh drain had a BOD of 34 mg/l and 42 mg/l in the corresponding months (60 mg/l in Oct). But the water quality of other drains like Sen’s Nursing, Tughlakabad, Maharani, Shahdara etc was much worse, yet the BOD levels of the river at the Okhla Barrage and downstream showed improvement in Nov (14 mg/l) and Dec (17 mg/l).

It was 20 mg/l at the Okhla Barrage in Oct.“This makes little sense. If downstream drains are more polluted, then the pollution load of the river must increase, but it is not happening in the reports,” Kumar said.