NEW DELHI: Data from the Delhi Pollution Control Committe (DPCC) on the Yamuna water quality for the month of May shows a decline in faecal coliform levels at several points along the river, even as marked deterioration was observed at some points. This indicates 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, which often leads to oxygen depletion and hence causes harm to aquatic life.
The water quality testing by the DPCC involves collecting water samples from eight locations along the course of the Yamuna in the city, gauging several parameters such as BOD, dissolved oxygen, chemical oxygen demand, pH and faecal coliform content, to determine the pollution level.
Among these locations are Palla, Wazirabad, ISBT bridge, ITO bridge, Nizamuddin bridge, Hindon Cut, Okhla barrage and Asgarpur in Haryana’s Kidwali.
While five of the points showed a 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 report showed slight improvement at ISBT bridge, but levels of faecal coliform remained as high as 1,30,000 most probable number (MPN) per 100 ml as compared to 1,70,000 MPN/100 ml in April.
Four other locations that saw an 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 1,50,000 MPN/100 ml in April to 1,20,000 MPN/100 ml in May; and
Nizamudin Bridge where the level improved from 140,000 MPN/100 ml to 110,000 MPN/100 ml.