Khulna: Three rivers—the Mayur, the Bhairab and the Rupsa— running beside the city are now under rampant human assaults due to encroachment and unchecked pollution.

The dumping of untreated industrial wastes and chemicals into the rivers from the metropolitan city and negligence of the authorities concerned have made way for illegal grabbers to stake substantial claims in those rivers.

Multiple industries have been set up on the banks of the Rupsa and Mayur, which affect the dissolved oxygen (DO) level in the waters, turning the water toxic and jeopardising the aquaculture in the process, reports the UNB.

Amid such troubled period, local experts feel the absence of a river research institute, which is only located in Dhaka and Faridpur.

According to sources at the Department of Environment, the oxygen level in the three rivers, along with the Kalibacha River, has reduced drastically. The oxygen level in the Mayur is alarmingly low.

Senior chemist at the department Md Kamruzzaman Sarkar said a river must contain above 4.5 mg of dissolved oxygen to sustain. In August, the DO level in the Rupsha river was 5.3 mg, the Bhairab 5.4 mg and the Mayur 1.2mg.

Though it is illegal to dump industrial waste and chemicals into the rivers without treatment, it is not being followed by the industries, an investigation reveals.

As a result, the expert said, the aquaculture is facing threat, while the nurseries built to cultivate spawn are also being polluted.

The presence of nearby jute mills, power plants, matchstick factories, brick kilns and Khulna City Corporation (KCC)’s dumping unit are greatly affecting the rivers.

It is alleged that the water in 22 canals and countless drains located in the Khulna City Corporation are rolled into the rivers without any proper filtering. The presence of human waste, dumped materials and other products are directly thrown into the rivers.

Dr M Rakib Uddin, a professor at Khulna University’s Environment science discipline, said this waste dumping is the main cause of pollution of the rivers, which are mainly caused by the nearby industries.

He also lamented the lack of a river research institute, which could have played a role in preventing such gross deterioration.

When asked, Habibul Haq Khan, director of the district’s environment directorate office, acknowledged the problems but said that lack of public awareness is also to be blamed.

He added that they carry out drives against the factories to prevent pollution, which will increase in the future.