Context: The Central Pollution Control Board (CPCB) has released its latest assessment report on river pollution across India, indicating a marginal improvement in water quality across the country’s rivers.
Key Findings:
- The report, based on water quality data collected from 2022 and 2023, highlights a slight reduction in the number of polluted rivers stretches—from 311 to 296—across 271 rivers in 32 States and Union Territories.
- Among the states, Maharashtra continues to have the highest number (54) of polluted river stretches.
- Out of 296 stretches identified as polluted, 37 were classified as the most polluted, or Priority I.
- These 37 stretches were identified across 14 states, with the highest number, five, in Tamil Nadu, Uttar Pradesh, and Uttarakhand; four in Gujarat, and three in Karnataka.
- Some of the most severely polluted stretches include:
- Yamuna (Delhi): From Palla to Asgarpur
- Sabarmati (Ahmedabad, Gujarat)
- Chambal (Madhya Pradesh): Nagda to Gandhisagar Dam
- Tungabhadra (Karnataka) and Sarabanga (Tamil Nadu)
Criteria parameter–
- Bio-Chemical Oxygen Demand (BOD)
- Identification of Polluted River Stretches (PRS)
Criteria for identification of PRS
- Stretches where the biochemical oxygen demand (BOD) exceeds 3 milligrams/litre (mg/L) are identified as polluted locations by CPCB.
- Two or more polluted locations identified on a river in a continuous sequence are considered as a stretch and defined as Polluted River Stretch.
PRS are categorized under five Priority Classes (I to V) on the basis of maximum BOD level observed.
- Priority – I: Monitoring locations exceeding BOD concentration 30.0 mg/ L
- Priority – II: Monitoring locations having BOD between 20.0 – 30.0 mg/ L
- Priority – III: Monitoring locations having BOD between 10.0 – 20.0 mg/ L
- Priority – IV: Monitoring locations having BOD between 6.0 – 10.0 mg/ L
- Priority – V: Monitoring locations having BOD between 3.0 – 6.0 mg/ L
