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Polluted River Stretches: CPCB Study

Polluted River Stretches: CPCB Study

Why in news?

  • The Central Pollution Control Board (CPCB) in 2018 identified 351 polluted river stretches in India.
  • CPCB study reveals that discharge of untreated wastewater is one of the main causes of river pollution.
  • The assessment of water quality for identification of polluted river stretches found that 31 states and Union territories (UT) had rivers and streams that did not meet the water quality criteria.

Findings of CPCB

  • Concentration of Polluted River Stretches: Almost 60% of polluted river stretches exist in eight states: Maharashtra, Assam, Madhya Pradesh, Kerala, Gujarat, Odisha, West Bengal and Karnataka.
  • Maharashtra has the maximum number of polluted river stretches in the country.
  • Disproportionate Sewage Treatment: The National Green Tribunal (NGT) in 2019 directed that 100% treatment of sewage needed to be ensured before 31st March, 2020.
  • However, these states have sewage treatment capacity disproportionate to the sewage generated.
  • According to the CPCB report National inventory of sewage treatment plants 2021, about 72,368 million litres per day (MLD) of sewage was generated against which operational treatment capacity was only 26,869 MLD in 2021.
  • Increasing Biological Oxygen Demand: This huge amount of sewage is left untreated/partially treated and discharged directly into rivers and pollutes rivers by increasing the biological oxygen demand.                                                                                  Polluted River Stretches: CPCB Study

Performance of states

  • Maharashtra has the highest number of polluted river stretches (53), followed by Assam (44), Madhya Pradesh (22), Kerala (21), Gujarat (20), Odisha (19), and West Bengal and Karnataka (17).                                                                          Polluted River Stretches: CPCB Study
  • The other less river polluted states are Delhi (1); Daman and Diu and Dadra and Nagar Haveli (1); Puducherry (2); Haryana (2); Rajasthan (2)

Steps taken by the govt

  • National Water Quality Monitoring Programme (NWMP): CPCB, in association with State pollution Control Boards / committees in different states / Union territories, have been monitoring the water quality of rivers and other water bodies across the country through a network of monitoring stations under the National Water Quality Monitoring Programme.
  • Cleaning / rejuvenation of rivers is an ongoing process. It is the responsibility of the states / UTs and local bodies to ensure the treatment of sewage and industrial effluents to the prescribed norms before discharging into water bodies, coastal waters, or land.
  • Namami Gange & NRCP: The Union ministry supplements efforts of states / UTs. It provides financial and technical assistance for abatement of pollution in identified stretches of rivers in the country through the Central Sector Scheme of Namami Gange for rivers in the Ganga basin, as well as through the Centrally Sponsored Scheme of National River Conservation Plan (NRCP) for other rivers.
  • NRCP: The river cleaning programme in the country initiated with the launching of the Ganga Action Plan (GAP) in 1985. The Ganga Action Plan was expanded to cover other rivers under National River Conservation Plan (NRCP) in the year 1995.
  • The objective of NRCP is to improve the water quality of the rivers, which are the major water sources in the country, through the implementation of pollution abatement works.


  • Maintaining Minimum Flow of the River: To maintain and restore the wholesomeness of the river (Aquatic ecosystem), there is a need to maintain the minimum flow.
  • Minimum flow of the river is also important to discharge treated sewage.
  • Comprehensive Waste Management Policy: There is a need for a comprehensive waste management policy that stresses the need for decentralised garbage disposal practices as this will incentivise private players to participate.                                                      Polluted River Stretches: CPCB Study
  • Bioremediation: It is important that Bioremediation (i.e. use of microbes to clean up contaminated soil and water) is made compulsory for areas wherever they can be applied.
  • Behavioural Change: To overhaul the waste management sector and induce the necessary behavioural change, citizen participation and engagement is the key.

Biological Oxygen Demand  

  • Biological Oxygen Demand is the amount of dissolved oxygen needed by microorganisms to decompose organic matter (waste or pollutants) under aerobic reaction (in the presence of oxygen).
  • The more organic matter there is (e.g., in sewage and polluted bodies of water), the greater is the BOD.
  • Greater BOD, the lower the amount of dissolved oxygen available for higher animals such as fishes.
  • The BOD is therefore a reliable gauge of the organic pollution of a water body.
  • One of the main reasons for treating wastewater prior to its discharge into a water resource is to lower its BOD i.e. to reduce its need of oxygen and thereby lessen its demand from the streams, lakes, rivers, or estuaries into which it is released.                                                  Polluted River Stretches: CPCB Study



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