The Buriganga River is one of the most polluted rivers in the world, in large part from the tanneries that operated here until many were relocated to Savar Tannery Park on the Dhaleshwari River in early 2018. Some smaller tanneries still operate on the Buriganga clandestinely and the government has not done much to shut them down. Though oxygen levels have improved, fish ingest the many heavy metals in the water. Some are carcinogenic and most are human health risks, yet despite its deadly waters this river remains a major artery of life for many of the people here. People work in the waters and it is the route by which many goods and services are transported. Children routinely play along the banks and under the drain pipes, while some even work in the industries located along the banks and have direct contact with this water on a daily basis.
The biggest threats to the Buriganga River are the dying factories at the Shuampur area, Dhaka WASA (Water Supply and Sewage Authority), continued unauthorized tannery operations, other industrial waste, and household pollutants. It is estimated that 60% of the pollution in the Buriganga come from industry, 30% from government institutions (WASA and others) and 10% from households. Most don't contain any sort of effluent treatment, and according to Abul Hasanat Abdullah, the chairman of the parliamentary standing committee on local government ministry, the city of Dhaka is only able to treat 20% of the cities sewage.
The lack of treatment causes water hyacinths to grow out of control and choke the river, totally clogging some canals and making them unusable. When hyacinths cover too much of the surface of the water, they block out all light and reduce oxygen levels. Fortunately, hyacinths can be harvested, chopped, ground, processed and dried into bricks that can be used for cooking oil and other energy needs. The World Health Organization attributes 4.3 million premature deaths worldwide to the burning of biomass and coal, so finding alternative sources for energy production seems wise for the air as well as the water. Water hyacinths are also used for water treatment in Southeast Asia.
In the distant past, the Ganges River flowed to the Bay of Bengal via the Dhaleshwari River. Over time, the course of the river shifted and lost its link with the Ganges, which is when it was renamed the Buriganga River. The Buriganga was linked with the Dhaleshwari though canals, but real estate companies, power companies, and brickfields have grabbed these canals and filled them in. The Buriganga has been robbed from connection to its source and this has worsened pollution levels, since freshwater no longer flows freely from the rivers it was once a tributary of. The river would be in even worse shape if it were not for the monsoons and flooding that accompanies these storms and adds fresh rainwater to this ailing river. The flooding associated with climate change is problematic though, since it erodes the banks and allows mosquitoes carrying many diseases to proliferate.