Significant increase in Yamuna pollution since 2017: Report

As the Delhi government has promised to clean the Yamuna to bathing standards by 2025, the pollution load in the river has increased substantially over the last five years, according to a report by the environment department. The report shows that barring Palla, the annual average concentration of biological oxygen demand (BOD) increased at every location of water sample collection for testing in the national capital.BOD, an important parameter for assessing water quality, is the amount of oxygen required by aerobic microorganisms to decompose organic material present in a water body. BOD levels less than 3 milligram per litre (mg/l) is considered good.There was no reaction available from the environment department. The Delhi Pollution Control Committee (DPCC) collects river water samples at Palla, where the Yamuna enters Delhi; Wazirabad, ISBT bridge, ITO bridge, Nizamuddin bridge, Agra Canal at Okhla Barrage, Okhla Barrage and Asgarpur. The DPCC data showed while there has been no major change in the annual average BOD level at Palla over the last five years (from 2017 to 2022), it has increased from around 3 mg/l to around 9 mg/l at Wazirabad.The BOD level has risen from around 30 mg/l to 50 mg/l at the ISBT bridge and from 22 mg/l to 55 mg/l at the ITO bridge during the period.Similarly, the BOD level worsened from 23 mg/l to around 60 mg/l at Nizamuddin bridge, from 26 mg/l to 63 mg/l at Agra Canal at Okhla Barrage, from 26 mg/l to 69 mg/l at Okhla Barrage and from around 30 mg/l to 73 mg/l at Asgarpur, the data showed.The Yamuna river can be considered fit for bathing if BOD is less than 3 milligram per litre and dissolved oxygen (DO) is greater than 5 milligram per litre.Dissolved oxygen (DO) is the amount of oxygen available to living aquatic organisms. Aquatic life is put under stress if DO levels in the water drop below 5 mg/l.Untapped wastewater from unauthorised colonies and jhuggi-jhopri clusters, and poor quality of treated wastewater discharged from sewage treatment plants (STPs) and common effluent treatment plants is the main reason behind high levels of pollution in the Yamuna.Delhi generates around 769 million gallons of wastewater a day. The 35 STPs located at 20 locations across the city can treat up to 632 MGD of sewage and have been utilizing around 90 per cent (570 MGD) of their capacity.