Widespread encroachment and mindless dumping of untreated waste are gradually killing the Karnaphuli River, the lifeline for Chittagong city and the country's premier port.

But the authorities have apparently turned a blind eye to it.

They are yet to demarcate the river boundary, leaving scope for land grabbers to encroach on the river, especially on its 24-kilometre stretch from Mohora to Patenga estuary.

In a survey in August, the district administration marked around 2,500 illegal structures in that part of the river.

The survey was conducted following a High Court directive in July 2010. The court order came upon a writ petition by Human Rights and Peace for Bangladesh that year.

"We will follow the court directive to evict those [illegal structures]," Deputy Commissioner Mesbah Uddin, who led the survey team, told The Daily Star recently.

During a visit to Kalurghat and Shah Amanat Bridge areas a week ago, this correspondent saw more than a dozen newly-built structures on the riverbank.

The width of the Karnaphuli has shrunk considerably due to encroachment.

The Hydrographic Survey Chart 1989-90 shows the river's width at 870 metres at Bridgeghat point while the 2009-10 chart puts it at 600 metres.

Apart from encroachment, indiscriminate dumping of untreated sewage and industrial waste is taking its toll on the Karnaphuli.

One-third of 1,200-1,400 tonnes of solid waste as well as liquid waste from the city of six million go to the river through 30 canals every day, as Chittagong Water Supply and Sewerage Authority is yet to set up plants for treating waste.

Contacted, Chittagong Wasa Secretary Shamsuddoha said, "A consultation team is working on sewage treatment plant project. It will submit a master plan by 2017. Once we get the plan, we will be able to start the project with World Bank's assistance," he said.

To make matters worse, a large number of factories are discharging an enormous quantity of untreated waste into the river daily.

Environmentalist Edris Ali, also vice president of Chittagong chapter of Bangladesh Paribesh Andolon, said around 800 industries dump untreated waste into the river every day. 

A building is being constructed on a grabbed portion of the Karnaphuli river, to the south of Kalurghat bridge in Chittagong. The photo was taken on Saturday. Photo: Anurup Kanti Das

"In most private industries, Effluent Treatment Plants are kept for show. Industry owners often avoid using them, as it increases production cost. The Department of Environment seldom monitors and takes action against these industries," he said.

Asked about this, DoE officials said around 150 of the 800 factories discharge hazardous waste into the river, and only 15 of them don't have ETP.

Mokbul Hossain, DoE director for Chittagong region, was not available for comments, as he is abroad.

Despite repeated attempts, DoE Director General Raisul Alam Mondal couldn't be reached over the mobile phone.

Seeking anonymity, a DoE official, however, said they monitor the factories regularly and take action if any of them is found guilty of not using ETP.

On the pollution level of the river water, Edris said, "Water quality indicators, including dissolved oxygen, are found below the standard level."

The water may not seem much polluted since it is not black all the time. But decreasing biodiversity of the river is a clear indication of its poor state, said Idris, who has been doing research on the river water since early 1990s.

"Had there been no tide, the river would have died years ago," said Edris, associate professor of chemistry at Government Mohsin College.

In a 2009 survey, Manzoorul Kibria, associate professor at Chittagong University, found only 50 types of fish in the river whereas the number was 140 in 1986.

Unlike in the past, Hilsa can hardly be found in the Karnaphuli now.

Dolphins were seen in large numbers in the river a decade ago, but now they have become a rare sight, say locals.