Experts of a special team have recently released test results from water samples they collected from the Halda River, finding it to be extremely polluted.
Comprised of members from Chittagong University and the district Weather Department, they had collected water samples from ten different parts of the Halda.
For the past few days, locals have been complaining of scores of dead fish floating on the river at a 15-km stretch.
Due to the polluted waters, various species of fish such as Ruhi, Katal, Ayeer, Chingri and several other types have been floating dead.
Locals said that they had initially spotted small dead fish floating on water, but from Thursday they started to notice large-sized fish, including a 15kg Mrigel, which was later buried.
Water experts have blamed this on two key factors, first its three feeder canals becoming polluted and second, the level of oxygen marking sharp fall in the river water.
Members of the experts’ team said that on an average, a liter’s worth of water contains 0.05mg of oxygen, but Halda currently contains less than 0.02mg of oxygen, which is not suitable for aquatic animals to survive in the river, resulting in deaths.
A Halda researcher and Professor of Zoology at Chittagong University Dr Md Manzoorul Kibria said that despite working on the river for over two decades, he has never witnessed such depths of pollution.
He mentioned about the low level of oxygen in the river water, saying that the an eight km stretch from Azimer Ghat to Raozan was the most polluted part of the river.
He also added that this would have been even less noticeable had the flash floods not occurred in the nearby Raozan, Fatikchhari and Hathazari regions.
The floods which increased the water level of the Halda and then gradually decreased made way for the dead fish to float on water.
The river has also blackened in texture, spreading a foul stench as well.
Professor Kibria said that the sample report has been sent to the concerned authorities for further inspection and necessary actions.