Concerns over river pollution levels and the effects on aquatic life have been raised since February, when data on Yamuna water quality became unavailable.
New Delhi, Since February, when the Delhi Pollution Control Committee (DPCC) last uploaded a monthly report on its website with parameters like biological oxygen (BOD), dissolved oxygen (DO), and faecal coliform, no information has been made available regarding the water quality of the Yamuna or the main drains that bring sewage and effluents into it.
The National Green Tribunal (NGT) ordered that water samples be taken from the Yamuna and from all main drains that discharge into the river; the samples were to be analysed and full reports were to be uploaded on the NGT’s website; however, for the past four months, this has not been done. According to experts, the data is required to analyze the river water’s quality over the short- and long-terms.
Questions on why the data was no longer being posted or if the body had stopped collecting samples entirely were submitted by HT to the Delhi government, the DPCC, and the principal secretary (environment & forest). All three parties did not respond. The NGT directed in 2019 that monthly statistics be posted on the DPCC website, with reports accessible for the Yamuna from January 2013 and the Delhi sewers since July 2019.
The Delhi Sewage Treatment Plants (STPs) and Common Effluent Treatment Plants (CETPs) reports are also uploaded by DPCC; the most recent reports are accessible through May of current year.
Palla (where the river enters Delhi), Wazirabad, ISBT Kashmere Gate, ITO bridge, Nizamuddin bridge, Okhla barrage, Agra canal, and lastly Asgarpur (where the river exits Delhi) are the eight points from which water samples are manually taken from the Yamuna. This covers metrics like pH, faecal coliform, chemical oxygen demand (COD), BOD, and DO. Over 25 drains in Delhi undergo similar testing.
BOD shows how much oxygen a river’s aquatic life and other species need to survive. The harder it is for aquatic life to survive, the higher the BOD. A river’s BOD level should be 3 mg/l or less, but according to the most recent report from February, it was only 1.3 mg/l at Palla, exceeding the limit. From there, it rose to 6.7 mg/l in Wazirabad and 41 mg/l by the time the river reached ISBT Kashmere Gate. The highest concentration was 54 mg/l at Asgarpur.
In order to detect the presence of sewage and human waste in the river, the monthly reports also measure faecal coliform, a type of bacterium found in the intestines of warm-blooded mammals, including humans. According to the February report, this varied from 2,000 parts per million (PPM) at Palla to 250,000 PPM as it leaves Delhi at Asgarpur. 2,200 PPM is the permissible maximum for faecal coliform.
When the DPCC released its most recent monthly report on Delhi’s 28 drains that same month, it revealed that seven of them had “no flow,” which indicates that at the time of sample collection, neither stormwater nor sewage was passing down the drain. Out of the 21 drains that were left, none of them fulfilled the 30 mg/l BOD requirement for drainage. The Sonia Vihar drain had the highest reading, 65 mg/l.
“It is challenging to determine whether the Yamuna is getting better or if things have gotten worse due to the lack of data,” stated Bhim Singh Rawat, a Yamuna activist and participant in the South Asia Network on Dams, Rivers, and People (SANDRP).
In order to acquire 22 online monitoring stations (OLMS) before the end of the year, which will be erected along the Yamuna to obtain real-time data on water quality, the DPCC had put out a tender in May.
Fish corpses in the Yamuna In recent days, images of dead fish floating in the Yamuna have also surfaced. These images are a sign of low BOD and DO, but experts noted that it is difficult to pinpoint the precise cause of the fatalities due to lacking data. According to locals, dead fish started to appear along the river floodplain approximately two weeks ago. However, following showers in the previous several days, the situation has improved.
We were receiving several kilograms of dead fish washing up on the riverbank till a fortnight ago. The Yamuna’s water quality looked to be far poorer then than it is now, and the river’s flow was not as powerful. The river is noticeably cleaner now that more water is being released from the Haryana side as well, according to fishermen Ram Sahni, who searches for his daily catch north of Palla.
When the water levels are low and a lot of effluent is dumped into the Yamuna, dead fish frequently wash up on the banks of the river, according to Trilochan Singh, a resident of Sabhapur village, which is close to Sonia Vihar.
It has been approximately ten days since we last heard of dead fish washing up on the floodplains. As the water level has risen, no fatalities have been reported in Delhi since it started to rain. The river in Haryana becomes a vivid shade of crimson in certain places due to the frequent releases of chemicals into it by tanneries. When this occurs, we frequently witness dead fish,” Singh said.
According to Faiyaz Khudsar, the scientist in charge of DDA’s biodiversity parks program, a significant amount of sewage and effluents typically cause a river’s oxygen levels to plummet.
“A large amount of water needs to be released from the Hathanikund barrage, which washes away the pollutants, for the dissolved oxygen to improve. It seems that the DO has been improving gradually since the rains started last week, according to Khudsar, who added that he last saw pictures of dead fish beside the river on June 30. He remarked, “This is probably before the rains.”
But nobody truly knows since there is an unexplainable lack of data.