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Source: The post is based on the article “CPCB report shows fewer polluted river stretches, but worst ones remain unchanged” published in The Hindu on 26th December 2022.
What is the News?
According to a recent report from the Central Pollution Control Board (CPCB), the number of polluted stretches in India’s rivers has fallen from 351 in 2018 to 311 in 2022. However, the number of most polluted stretches is practically unchanged.
About the working of CPCB report on water quality
The CPCB network monitors water quality at 4,484 locations across the country.
Conditions for determining water quality: a) Biochemical oxygen demand (BOD) exceeding 3 milligrams per litre (mg/l) is identified as polluted locations, b) A BOD less than 3 mg/l means the river stretch is fit for “outdoor bathing,” and c) Two or more polluted locations identified on a river in a continuous sequence are considered as a “polluted river stretch.
Categorisation: There are five priority categories. 1) BOD exceeding 30 mg/l are considered “Priority 1” (P1), meaning, the most polluted and thus needing the most urgent remediation, and 2) The rest of the categories “Priority 2” (P2) to P5 were defined based on BOD less than 30mg/l.
Significance: The success of river-cleaning programmes are measured by the number of stretches moving from 1 to 2, 2 to 3 until those in 5 (requiring the least action) to reduce.
Reason for the report: The National Green Tribunal passed orders that the CPCB and the Jal Shakti Ministry monitor river pollution and ensure that it was dealt with. Every State had to ensure that at least one river stretch was “restored” to at least be fit for bathing.
About the recent CPCB report on water quality
There is almost no change/slight change in the P1 and P2 categories of polluted river stretch from 2018 and the present report. This indicates that further stringent actions are required for control of organic pollution from various point sources of pollution including the development of infrastructure and its proper operation for treatment of wastewater before discharge into recipient water bodies,
Performance of states: Gujarat and Uttar Pradesh had the highest number of “Priority 1” river stretches (6). Maharashtra had the most polluted river stretches of 55, followed by Madhya Pradesh (19), Bihar (18), and Kerala (18).
The overall decrease in the net number of identified polluted river stretches, which have shown improvement in water quality, “could be attributed” to the efforts done for infrastructure development for pollution control.