Why the Yamuna in Delhi froths every year: An explainer

Updated on Oct 28, 2022 02:37 PM IST

Every year on Chhath, thousands of devotees take a dip in the river at several ghats to celebrate the four-day festival. Last year too, hundreds of devotees were seen taking a dip in the river at Kalindi Kunj despite a heavy layer of foam over the water surface

A thick layer of foam blankets the Yamuna river near Kalindi Kunj on Thursday. (Sanjeev Verma/HT Photo) PREMIUM
A thick layer of foam blankets the Yamuna river near Kalindi Kunj on Thursday. (Sanjeev Verma/HT Photo)
By, New Delhi

Days before Chhath Puja, a thick layer of foam was seen floating over the Yamuna on Thursday, indicating high levels of untreated sewage and industrial pollutant in the river’s water.

The foam, experts said, is an annual phenomenon during winters, and is a clear symptom that indicates that the river stretch in Delhi is “dead”.

Every year on Chhath, thousands of devotees take a dip in the river at several ghats to celebrate the four-day festival. Last year too, hundreds of devotees were seen taking a dip in the river at Kalindi Kunj despite a heavy layer of foam over the water surface.

According to a Yamuna Monitoring Committee report in 2018, the stretch of the Yamuna in Delhi accounts for around 2% of the length of the river but contributes to over 75% of the river’s pollution. The committee had been formed by the National Green Tribunal to find solutions to the river’s problem, which included froth formation and a subsequent report in 2020, jointly submitted by the Delhi Pollution Control Committee (DPCC) and the Central Pollution Control Board (CPCB) had found the presence of high amount of phosphates, primarily released from detergents to be key cause of foam.

According to the latest DPCC’s latest report, the agency analysed water samples from eight prominent Yamuna ghats in September. It said that the sample from only one ghat, Palla, met the biological oxygen demand (BOD) of 3 mg/l or less, and only two ghats – Palla and Wazirabad -- met the dissolved oxygen (DO) standard of 5 mg/l or higher.

BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria.

Faecal coliform, which indicates the presence of untreated sewage in the water, ranged from four times the permissible limit at Palla to as high as 244 times the standard limits at Asgarpur, where the river leaves Delhi, the DPCC report said.

Why problem persists

In June, 2021, DPCC had banned the sale, storage, transportation, and marketing of soaps and detergents not meeting BIS norms. But experts said that the ban was not enforced properly and untreated sewage continues to flow into the river.

“Every year, we see froth formation around this time as the temperatures are low and water flow is slower. Phosphates from detergents and industrial effluents are the major cause of foam formation. Until these are stopped, this will continue to happen,” said Manoj Misra, convener of the Yamuna Jiye Abhiyaan.

Bhim Singh Rawat, a Yamuna activist and part of the South Asia Network on Dams, Rivers and People (SANDRP) said until sewage continues to be dumped into the river, the water quality is unlikely to improve. “Sewage, industrial effluents and detergents and dyes all lead to different problems for the river. Controlling flow of detergents and industrial effluents into the river can stop froth formation, and trapping of all sewage will improve the river’s water quality,” said Rawat. He added that the froth problem is particularly acute near Okhla Barrage as water full of phosphates falls from a height there, aiding the formation of foam.

A joint committee of stakeholders comprising of the National Mission for Clean Ganga (NMCG), Upper Yamuna River Board (UYRB), Delhi Jal Board (DJB) and DPCC was constituted on October 17 in order to minimise and control froth formation ahead of Chhath.

Increased water flow will help

Misra said ensuring increased flow of water in the river can help stop formation of foam ahead of Chhath and also improve water quality. “If 2,50,000 cusecs of water is released each day from the Hathinikund Barrage till Chhath, all this foam will disappear, and the river will also look cleaner. The government can write to their Haryana counterparts to release more water,” he said.

Delhi Jal Board (DJB) that operates water treatment plants and DPCC did not respond to HT’s queries on the river quality.

A Delhi government official they were spraying anti-foam chemicals in the river. “The DJB is regularly monitoring the parameters downstream of Okhla Barrage through its Okhla Sewage Testing Laboratory that is an ISO and NABL accredited laboratory. The reports of the fresh tests done at the lab show that the quality parameters of Yamuna water has improved after the spray,” said the official who asked not to be named.

Health experts warned that Chhath devotees should avoid the polluted section of river as the toxic froth can lead to gastrointestinal problems, water-borne disease such as typhoid and skin allergies.

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