DELHI: Data shows that the number of polluted river stretches has reduced in the past three years. However, eighteen states and union territories have 46 river stretches that are highly polluted beyond their threshold level. UP and Gujarat have the highest number of river stretches among them.
The number of polluted river stretches was reported to be 351 in the year 2018 on 323 rivers. Water quality is based on excesses of the Bathing Water Quality Criteria parameter of Biological Oxygen Demand (BOD) which exceeds 3 mg/L. The same criteria were adopted in 2016 and 2017 to measure water quality on river stretches.
BOD measures the amount of oxygen required to remove waste organic matter from water. It means the highest BOD, the lowest quality of water. The fair amount of BOD level should be lesser or equal to 3 mg/litre to take bathe in the open.
Ashwini Kumar Choubey, Minister of State in the Ministry of Environment, Forest and Climate Change, tabled the information in the Rajya Sabha, stating that the number of polluted river stretches was reduced.
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In his written reply, Minister informed the parliament that the number of polluted river stretches reduced to 311 in 2022. The water quality data analysis of the same river stretches was also done in 2019 and 2021.
However, in these years, the number of rivers has reduced. Between 2016-2018, the samples were taken from 323 rivers, and the number of samples were taken from 279 rivers in the past three years.
Between 2019 and 2022, the Central Pollution Control Board (CPCB) identified 311 polluted stretches on 279 rivers.
Polluted River stretches (PRS) are categorized under five Priority Classes (I to V) based on the maximum BOD level observed. It means the higher the BOD lesser the priority class.
Under priority Class I, which has a higher BOD than 30 mg/L, 46 polluted river stretches were identified in 18 states and union territories.
The highest number of PRS are identified in Gujarat& Uttar Pradesh (6 each), followed by Himachal Pradesh, Maharashtra & Tamil Nadu (4 each); Karnataka & Punjab (3 each); Haryana, Madhya Pradesh, Meghalaya, Rajasthan &Uttarakhand (2 each) and one each in Telangana, Andhra Pradesh, Assam, Delhi, West Bengal and Odisha.