The Central Pollution Control Board’s assessment of 17 polluted river stretches in West Bengal reveals a water-quality crisis that extends beyond individual rivers. The Hooghly, Damodar and Adi Ganga are among the water systems identified, while readings from several locations show that organic pollution is not a marginal problem but a direct measure of how poorly sewage and waste are being managed across the state’s urban and peri-urban landscape.
The assessment, reported by Sanmarg on the occasion of World Rivers Day, points to two linked pressures: sewage entering river systems and declining water flow. Together, they reduce the ability of rivers to dilute or carry away pollutants. The result is a water-quality problem that is visible at the riverbank but produced by systems located across the city and its surrounding settlements.
The Adi Ganga offers the clearest example. A water sample collected near Jeerat Bridge in November last year was described as black and foul-smelling. The reported biochemical oxygen demand, or BOD, was 18.5 milligrams per litre, while dissolved oxygen was only 2 milligrams per litre. Faecal coliform levels were also reported to be high.
These measurements matter because they describe the condition of the water rather than merely its appearance. BOD indicates the amount of oxygen required by microorganisms to break down organic matter in water. A high BOD suggests a substantial presence of biodegradable pollutants. Dissolved oxygen, by contrast, indicates how much oxygen remains available in the water. When it falls, aquatic life faces more difficult conditions and the river’s ecological functions weaken.
The reported figures from other stretches are even higher. The Churni recorded a maximum BOD of 20.8 milligrams per litre in the Bijaypur-Ranaghat section. In the Harua-Malancha stretch of the Bidyadhari, the reported maximum was 29.6 milligrams per litre. The Mahananda reached 31 milligrams per litre near Siliguri. The supplied report does not provide the full list of all 17 identified river stretches or the complete set of parameters used in the assessment, but these readings show the scale of the problem at the locations cited.
The pattern is important for understanding how river pollution operates in Bengal. It is not confined to a single metropolitan waterway or to one industrial corridor. The cited stretches include rivers associated with Kolkata, southern Bengal and north Bengal. This distribution suggests a governance challenge spread across multiple urban bodies, local administrations and river basins rather than one isolated pollution event.
For Kolkata, the Adi Ganga’s condition is particularly significant because the waterway passes through a dense urban environment. Its pollution is therefore connected to the everyday functioning of neighbourhoods: the collection and treatment of sewage, the condition of drains, the management of informal discharge points and the quantity of water moving through the channel. The report does not identify the precise contribution of each of these factors, but its reference to sewage and declining water flow places both within the central policy problem.
The distinction between a river and a drain is also relevant to urban planning. When a waterway receives untreated or inadequately treated sewage, its ecological role is gradually replaced by a conveyance role for waste. A low-flow river has less capacity to absorb that load. The visible symptoms—dark water, odour and low dissolved oxygen—are therefore downstream signs of failures in sanitation infrastructure and water management.
The CPCB assessment also highlights the limits of measuring river health through isolated clean-up activity. River restoration cannot be judged only by the appearance of a riverfront or by the removal of surface waste. BOD, dissolved oxygen and faecal contamination provide a more meaningful picture of whether pollution loads are being reduced and whether the river is regaining ecological capacity. In the cited locations, the reported readings indicate that the underlying pollution burden remains serious.
Institutional responsibility is likely to be distributed across agencies. Pollution control authorities monitor water quality and identify polluted stretches, while municipal and other local bodies are responsible for parts of the sewage and drainage system. River-flow conditions are influenced by factors beyond a single city authority. The supplied report does not establish which agency is responsible for each cited stretch, what treatment capacity is available, or whether specific remediation deadlines have been set. Those gaps are important because identification is only the first stage of river governance.
The numbers also make the challenge measurable. Adi Ganga’s reported BOD of 18.5 milligrams per litre is followed by higher reported readings of 20.8 in the Churni, 29.6 in the Bidyadhari and 31 in the Mahananda. These are not comparable with a general description of pollution alone; they establish a gradient of severe organic loading across different river systems. At the same time, the report does not provide a historical series, so it cannot establish whether conditions are improving or worsening at each location.
That missing trend data is central to evaluating public programmes. A single sampling exercise can identify a serious condition, but repeated monitoring is needed to determine whether interventions are working across seasons. River pollution can vary with rainfall, flow, discharge patterns and the operation of treatment facilities. The reported November sample from the Adi Ganga offers a specific warning, but the available material does not show how its readings compare with other months or previous years.
The public-health and urban consequences are also broader than the river channel itself. High faecal contamination and foul-smelling water indicate exposure risks around polluted stretches, while low dissolved oxygen signals damage to aquatic conditions. The supplied report does not quantify health impacts or identify affected communities, so those consequences should not be overstated. What is established is that polluted rivers pass through populated areas and reflect deficiencies in systems that cities depend on for sanitation and environmental safety.
West Bengal’s 17 identified polluted stretches therefore represent a test of whether river management is being treated as an environmental issue alone or as part of core urban infrastructure. Sewage networks, treatment plants, drainage channels, monitoring systems and river-flow management are interconnected. Failure in one part can undermine the others, even when a clean-up programme addresses the riverbank itself.
The CPCB assessment establishes the scale and location of a serious problem, while the reported readings show that organic pollution is particularly acute in several stretches. It does not, on its own, establish the precise source of every discharge, the performance of treatment infrastructure or the timeline for remediation. Those are the facts that need to be tracked next. Until they are publicly connected to measurable improvements in BOD, dissolved oxygen and faecal contamination, the listing of 17 polluted river stretches will remain less a diagnosis completed than a warning about the state’s urban water systems.
