News: The CPCB’s latest assessment indicates a slight decline in the number of polluted river stretches across India.
About polluted river stretch
- According to CPCB, a “polluted river stretch” is where two or more polluted locations occur in a continuous sequence on a river where BOD levels exceed 3 mg/L, rendering water unfit for bathing.
- Classification of Pollution Levels
- CPCB categorizes polluted river stretches into five priority categories based on BOD.
- Priority Class V: BOD 3.1–6 mg/L (least polluted, needs low intervention).
- Priority Class I: BOD exceeding 30 mg/L (most polluted, needs urgent attention).
- BOD < 3 mg/L: Generally fit for bathing.
Findings of CPCB Report on River Pollution
- Marginal Improvement: The Central Pollution Control Board’s (CPCB) 2023 assessment shows a slight improvement in river water quality, with the number of polluted stretches reducing from 311 in 2022 to 296 in 2023, covering 271 rivers across 32 states and Union Territories.
- Most Affected States: Maharashtra remains the worst affected with 54 polluted river stretches. Other states with significant pollution include Kerala (31), Madhya Pradesh and Manipur (18 each), and Karnataka (14).
- Priority Classifications
- Priority I (BOD > 30 mg/L) – Most polluted stretches needing urgent intervention dropped from 46 in 2022 to 37 in 2023. Notable examples include the Yamuna (Delhi), Sabarmati (Ahmedabad), Chambal (Madhya Pradesh), and parts of the Tungabhadra and Sarabanga rivers.
- Priority V (BOD 3.1–6 mg/L) – Less polluted stretches requiring minimal intervention.
- Rivers Showing Deterioration: Despite overall gains, certain rivers show worsening quality, including the Jhelum (J&K), Ganga and Sikrahna (Bihar), Hasdeo and Mahanadi (Chhattisgarh), Cauvery and Tungabhadra (Karnataka), Periyar (Kerala), and Krishna (Telangana).
- Long-Term Monitoring: CPCB, along with State Pollution Control Boards, monitors water quality at over 4,700 locations under the National Water Quality Monitoring Programme, tracking rivers, lakes, drains, and canals.
- Institutional Interventions: Following the 2018 National Green Tribunal (NGT) directive, all states are required to develop river rejuvenation action plans. The current CPCB report highlights catchment area management, sewage treatment, and floodplain protection as key measures to control river pollution.
