More river stretches are now critically polluted: CPCB

More river stretches are now critically polluted: CPCB

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1.  According to an assessment by the CPCB, the number of polluted stretches in India’s rivers have increased.

Important facts

2.  Central Pollution Control Board (CPCB) is a statutory organization established in 1974 under the Ministry of Environment and Forest.
3.  National Green Tribunal (NGT) has been established in 2010 under the National Green Tribunal Act 2010 for effective and expeditious disposal of cases relating to environmental protection, conservation of forest etc.
4.  Biochemical oxygen demand (BOD) is the amount of dissolved oxygen used by microorganisms in the biological process.

• The greater the BOD, the lower is the amount of dissolved oxygen available for marine animals.
• It is a reliable gauge to measure organic pollution in water bodies.

5. CPCB has a programme of measuring the quality of rivers based on BOD since 1990s.
6. The health of a river and efficiency of the water treatment are classified based on BOD.

The greater the BOD the higher is the priority level.

• BOD greater than or equal to 30 mg/l is categorized as Priority 1.
• BOD between 3.1- 6 mg/l is termed as Priority 5.

7.  The CPCB considers a BOD less than 3 mg/l an indicator of a healthy water body.
8.  Central Pollution Control Board (CPCB) conducted an assessment of the pollution in Indian rivers based on the recommendations of the National Green Tribunal (NGT).
9.  The report has not been published yet.

Findings of the Assessment

10. The number of polluted stretches in India’s rivers have increased to 351 from 302 in 2015.
11. The number of critically polluted stretches where water quality indicators are the poorest has also gone up to 45 from 34.
12. Although the focus is mainly on Ganga and the states through which it flows, it has been found that many rivers in Maharashtra, Assam and Gujarat are far more polluted.
13. These three states account for 117 of the 351 polluted river stretches.
14.  Some of significant stretches of pollution includes the

• Mithi river between Powai and Dharavi, BOD level of 250 mg/l
• Godavari from Someshwar to Rahed, BOD level of 5.0-80 mg/l
• Sabarmati between Kheroj to Vautha, BOD level of 4.0-147 mg/l
•  Hindon between Saharanpur to Ghaziabad, BOD level of 48-120 mg/l

15. In contrast, the pollution level of Ganga in stretches of Uttar Pradesh has BOD range of 3.5-8.8 mg/l and is categorized as a Priority 4 river.
16. The increase in numbers reflects higher pollution level as well as an increase in water quality monitoring stations.