West Bengal sees major improvement in Ganga pollution levels: Namami Gange
The mission said although the polluted stretch appears geographically longer in the latest assessment, the actual pollution load has reduced considerably
New Delhi: West Bengal, the last main-stem state on the Ganga before the river empties into the sea, is showing a significant improvement in pollution levels, despite carrying the cumulative sewage and industrial load of all upstream states, according to Namami Gange.
In a post on X, the National Mission for Clean Ganga (NMCG) said the final stretch of the river in West Bengal “carries everything” flowing downstream from the Himalayas through the densely-populated Ganga basin.
“The Ganga’s last stretch carries everything. By the time the river reaches West Bengal, it is carrying the cumulative load of every state upstream, every city, every drain, all the way from the Himalayas,” Namami Gange said.
“And this is the stretch that has improved the most,” it added.
The mission cited the Central Pollution Control Board’s (CPCB) Polluted River Stretches (PRS) assessment to underline the change in the water quality over the last seven years.
According to Namami Gange, the Triveni-to-Diamond Harbour stretch of the river in West Bengal was categorised as a “Priority III” polluted river stretch in 2018. In the CPCB’s 2025 assessment, the flagged stretch has shifted to Baharampore-to-Diamond Harbour and is now categorised as “Priority V”.
The mission said although the polluted stretch appears geographically longer in the latest assessment, the actual pollution load has reduced considerably.”That sounds counterintuitive until you read it correctly: a longer line on the map, but far less pollution in the water,” it said.
The mission attributed this transformation to 34 sewage-infrastructure projects worth Rs 5,028 crore sanctioned so far in West Bengal under the Namami Gange programme, with a total sewage treatment capacity of 816 MLD (million litres per day).Of this, a total treatment capacity of 558.5 MLD across 17 projects has been completed, according to the mission.
Namami Gange said the infrastructure build-out is concentrated around the Hooghly belt, where the river receives heavy urban discharge from the Kolkata metropolitan region and adjoining towns.
Among the projects commissioned during Financial Year 2025-26 are the 35-MLD Maheshtala Sewage Treatment Plant (STP) built at a cost of Rs 287 crore, the 30-MLD North Barrackpore STP built at Rs 154 crore and designed to serve around 2.2 lakh people, the 13-MLD Jangipur STP built at Rs 68.47 crore and the 15-MLD Chakdah STP constructed at a cost of Rs 121.66 crore.
The mission also highlighted the growing use of the Hybrid Annuity Model (HAM) in Bengal’s sewage-infrastructure programme. Under HAM, private operators build and operate treatment plants, while payments are linked to long-term operational performance.
The Maheshtala, North Barrackpore and Chakdah projects are all being implemented under this model, Namami Gange said.
The mission also focussed on the East Kolkata Wetland, which it described as one of the world’s largest functioning natural wastewater treatment ecosystems.
“The most remarkable piece of infrastructure in Bengal was not built by anyone. The East Kolkata Wetland treats roughly 750 MLD of the city’s sewage naturally, using fish ponds, paddy fields and bacterial action, before the water even reaches the Hooghly,” Namami Gange said.
“It is a Ramsar site. It feeds the city with fish and vegetables. It is the largest natural wastewater treatment system of its kind in the world. Namami Gange’s work here complements that living system rather than replacing it,” the mission said.
According to the CPCB’s latest assessment cited by Namami Gange, most stretches of the Ganga in West Bengal now conform to bathing-quality norms, with only the lower Baharampore-to-Diamond Harbour stretch remaining under the Priority V category.
The mission noted that this stretch passes through the Kolkata-Howrah urban agglomeration, one of the densest population clusters anywhere along the Ganga basin.
“A Priority V rating there, after the Ganga has absorbed everything from upstream, is meaningfully better than where the river stood in 2018,” it said.
Namami Gange also said policy work related to the safe reuse of treated wastewater is nearing completion in West Bengal. The state’s Safe Reuse of Treated Water Policy is expected to be notified within the next two months, it added.
“The last stretch carries the most. And the work shows,” the mission said.