The Delhi Pollution Control Committee’s data on Yamuna water quality for May shows decrease in faecal coliform levels at several points along the river, even as marked deterioration was observed at some points, indicating that significant amounts of untreated sewage was still entering the river.
The report also shows high levels of Biological Oxygen Demand (BOD), a measure of the amount of dissolved oxygen required by microorganisms to break down organic matter in water. A higher BOD value indicates higher levels of pollution, often leading to oxygen depletion and harm to aquatic life.
The water quality testing by Delhi Pollution Control Committee (DPCC) involves collecting water samples from eight locations along the course of the Yamuna in the capital, gauging several parameters such as BOD, dissolved oxygen, chemical oxygen demand, pH and faecal coliform content, to determine pollution level.
These locations are Palla, Wazirabad, ISBT bridge, ITO bridge, Nizamuddin bridge, Hindon Cut, Okhla barrage and Asgarpur in Kidwali, Haryana.
While five of the points showed slight improvement in faecal coliform levels since April, the figures remained above the permissible limit of 2,500 and the desirable level of 500.
The May report showed slight improvement at ISBT bridge, but levels of faecal coliform remained as high as 130,000 Most Probable Number per 100 millilitres (MPN/100 ml), as compared to 170,000 MPN/100 ml in April.
The four other locations which showed improvement were Palla, where faecal coliform levels improved from 2,800 MPN/100 ml in April to 2,200 MPN/100 ml in May; Wazirabad where the level improved from 9,200 MPN/100 ml to 3,500 MPN/100 ml; ITO bridge where the level went from 150,000 MPN/100 ml in April to 120,000 MPN/100 ml in May; and Nizamudin Bridge where the level improved from 140,000 MPN/100 ml to 110,000 MPN/100 ml.
The river showed further deterioration at Asgarpur, where levels of faecal coliform remained as high as 330,000 (MPN/100 ml) in May, as compared to 310,000 in April.
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The pollution level has also deteriorated at the Okhla barrage, where the faecal coliform level touched 140,000 MPN/100 ml in May, as compared to 120,000 MPN/100 ml in April; and Hindon Cut where the level remained around 92,000 MPN/100 ml as compared to 54,000 MPN/100 ml in April.
BOD levels for May also showed alarming readings, ranging from 2-60 milligrams per litre (mg/l), while the water quality criteria stipulated a maximum of 3 mg/l, with the highest BOD recorded at Asgarpur at 60 mg/l. BOD at Asgarpur last month was 58 mg/l.
The DPCC has also uploaded the data for waste water quality at Delhi’s major drains for April, according to which several drains, discharging directly into the Yamuna, as well as supplementary drains of the Najafgarh canal showed high BOD and TSS (Total Suspended Solids) levels.
