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, though the number of most polluted stretches is practically unchanged.
- CPCB is mandated to collect, collate and disseminate technical and statistical data relating to water pollution under the Water (Prevention and Control of Pollution) Act, 1974.
Key points
- The CPCB network monitors water quality at 4,484 locations across the country.
- Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature.
- Biochemical oxygen demand (BOD) exceeding 3 milligrams per litre (mg/l) is identified as polluted locations.
- Two or more polluted locations identified on a river in a continuous sequence are considered as a “polluted river stretch.
- A BOD less than 3 mg/l means the river stretch is fit for “outdoor bathing.
- Further, stretches with BOD exceeding 30 mg/l are considered “Priority 1” (P1), meaning, the most polluted and thus needing the most urgent remediation.
- While 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).
