Pollution in Yamuna worsens 42 times when crossing Delhi

Delhi Pollution Control Committee's report shows Yamuna's BOD levels spiked to 85mg/l at Asgarpur, 28 times higher than Palla's 2mg/l, indicating worsening water quality.

The biological oxygen demand (BOD) levels in the Yamuna in June were 2mg/litre at Palla, where the river enters Delhi but rose to a deeply worrying 85mg/l at Asgarpur, where it exits Delhi, according to the latest water quality report uploaded by the Delhi Pollution Control Committee (DPCC) on Friday.

HT Image

The permissible BOD level in the river is 3mg/l. The difference in BOD levels at the two sites — Asgarpur recorded nearly 28 times more than Palla — is indicative of the decaying water quality in the river.

HT reported on Thursday that the agency had not uploaded the data on water quality since February — something it is mandated to do monthly by the National Green Tribunal, recording levels of BOD, dissolved oxygen (DO), chemical oxygen demand (COD), and faecal coliform.

Reports for March, March, April, May and June were uploaded by DPCC on its website on Friday, showing that the water quality in June this year was nearly two times worse compared to June 2023.

Water samples are collected manually from the Yamuna from eight locations by DPCC every month. The collection begins at Palla, where the river enters Delhi, followed by Wazirabad, ISBT Kashmere Gate, ITO bridge, Nizamuddin bridge, Okhla barrage, Agra Canal and Asgarpur.

BOD level deteriorated downsteamAccording to the data, while the BOD level was within limits at Palla, it started to deteriorate as the river flowed downstream. The level was 7mg/l at Wazirabad, 47mg/l at Kashmere Gate, 30mg/l at ITO bridge, 40 mg/l at Nizamuddin bridge and 50mg/l at Okhla Barrage. At Asgarpur, soon after the confluence of the Shahdara and Tughlaqabad drains, the BOD shot up to 85mg/l, highlighting the impact of sewage and effluents entering the river. This was worse than last June when the highest BOD recorded was 50mg/l at Asgarpur. May’s report also showed no significant improvement either, with the BOD going as high as 75mg/l.

The Delhi government did not comment on the worsening parameters of the river. DPCC, when contacted, did not share why data was not being updated until now.

To be sure, the heavy monsoon last year caused the Yamuna to swell beyond the danger mark, which played a role in improving the water quality in the river. The latest report, dated June 25, said that samples were collected by DPCC on June 3 when Delhi was in the middle of a heatwave and water crisis. The flow of the river also impacts the water quality — the higher the flow, the lesser the pollution. This year, Delhi recorded a dry May and June till June 28, when the monsoon hit Delhi. In comparison, over 200mm of rainfall was recorded in May and June 2023 and the flow was comparatively better.

BOD indicates the amount of oxygen required by aquatic life and organisms in the river to survive. The higher the BOD, the more difficult it is for aquatic life to survive.

DO denotes the amount of oxygen present in a water body for aquatic life to use and should be over 5mg/l in rivers. The June report showed the DO was 8.6mg/l at Palla, and 7.2mg/l at Wazirabad, but zero at all other stations barring 2.8 mg/l at ITO bridge. In May, DO was only recorded at these three stations and zero DO was found at the remaining five stations.

The monthly reports also measure faecal coliform — bacteria living in the intestines of warm-blooded mammals, including humans, thus indicating the presence of sewage and human waste in the river. This ranged from 1,600 parts per million (PPN) at Palla to 24,00,000 PPM at Asgarpur, according to the June report. The permissible limit is only 2,500 PPN.

Drains no betterDPCC is mandated by NGT to carry out a similar exercise for all major drains emptying into the Yamuna. The data for drains points out if sewage is flowing through the drains or reaching sewage treatment plants (STPs) instead. Of the 27 major drains assessed in June, 11 had “no flow” — no sewage or stormwater flowing through them, at the time of testing. The remaining 18 had a BOD value over the permissible standard of 30mg/l for drains. The highest value of 120mg/l was recorded at the Shahdara drain.

Images of dead fish floating in the Yamuna have also surfaced in the last few days – an indicator of low DO and high BOD.

Experts said the latest report confirms what environmentalists had been suspecting, adding Delhi the water quality does not improve as sewage continues to flow into the river. “Until we stop sewage from flowing into the Yamuna, the water quality will not improve, but simply fluctuate, depending on the environmental flow of the river. If Haryana releases more water, as it does during the monsoon period, parameters will improve again, but this is only a temporary improvement,” said Diwan Singh, an activist who took up the cause of Yamuna protection in 2007.

“The Yamuna has turned into a drain that is now solely dependent on water flow. Any improvement recorded is solely down to an increased flow of water and not because of the action by the government,” said Bhim Singh Rawat, a Yamuna activist, and member of the South Asia Network on Dams, Rivers and People.