CPCB report shows fewer polluted river stretches, but worst ones remain unchanged

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, according to a report from the Central Pollution Control Board (CPCB) in November but made public this week.

The CPCB network monitors water quality at 4,484 locations across the country.

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. There are five such categories with “Priority 2” (P2) indicating a BOD of 20-30 mg/l and “Priority 5” (P5) indicating 3-6 mg/l. The success of river-cleaning programmes are measured by the number of stretches moving from 1 to 2, 2 to 3 until those in 5 (requiring the least action) too reduce.

In 2018, when the CPCB published its report (after analysing stretches in 2016 and 2017), there were 45 stretches categorised in P1, 16 in P2, 43 in P3, 72 in P4 and 175 in P5. The latest report counts 46 in P1, 16 in P2, 39 in P3, 65 in P4 and 145 in P5. All of the improvement thus, were in river stretches that required relatively less intervention.

“No change/slight change in P1 and 2 category of polluted river stretches indicates that further stringent actions are required for control of organic pollution from various point sources of pollution including development of infrastructure and its proper operation for treatment of wastewater before discharge into recipient water bodies,” the CPCB report observes.

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), Bihar (18), Kerala (18), Karnataka (17) and Uttar Pradesh (17).

Following a report published in The Hindu in 2018, the National Green Tribunal passed orders that the CPCB and the Jal Shakti Ministry monitor river pollution and ensure that it was dealt with. Every State had to ensure that at least one river stretch was “restored” to at least be fit for bathing.

To questions on the status of river-pollution abatement efforts by States, Minister Prahlad Patel said pollution abatement work had been implemented in 36 rivers in 80 towns, spread over 16 States at a total cost of ₹6,248.16 crore, and a sewage treatment capacity of 2,745.7 million litres per day (MLD) has been created.

“Under the Central Sector Scheme of Namami Gange, 406 projects, including 176 projects for sewage treatment of 5,270 MLD and a sewer network of 5,214 km, have been sanctioned at a cost of ₹32,898 crore against which sewage treatment capacity of 1,858 MLD has been created so far,” he said in a statement.

The CPCB, in its report, added the overall decrease in the net number of identified polluted river stretches, which have shown improvement in water quality, “could be attributed” to the efforts done for infrastructure development for pollution control.