Water quality in Chattogram’s Karnaphuli River is degrading due to untreated sewage and industrial waste from the city. Ammonium and phosphate levels at different points along the river caused by sewage waste were nearly five times higher than normal, according to tests conducted by the Department of Environment’s laboratory. Water quality was found to be at its most critical in areas adjacent to TSP and CUFL. At the same time, the level of total dissolved solids (TDS) in the water has also increased abnormally in these areas. This poses a serious threat to aquatic life, fish breeding, and the overall ecological balance of the river.
Relevant stakeholders said thousands of tonnes of waste are flowing directly into the river every day through the city’s canals, making the Karnaphuli’s water unsuitable for use and placing the river’s biodiversity under severe threat. The normal movement of fish and other aquatic species has already declined in different parts of the river.
According to data from the Chattogram laboratory of the Department of Environment, water samples are collected every month from six points along the Karnaphuli River: areas adjacent to Karnaphuli Paper Mills, Mariumnagar, Sikalbaha, Kalurghat Bridge, the TSP factory, and the area near CUFL.
The acceptable level of ammonium in water is 0.3 milligrams per litre. The tests, however, found higher-than-normal concentrations at four points. Among them, ammonium levels were recorded at 0.22 milligrams per litre in the Karnaphuli Paper Mills area and 0.27 milligrams in Mariumnagar. Both close to the acceptable limit. The levels rose to 0.38 milligrams per litre in Sikalbaha, 0.56 milligrams near Kalurghat Bridge, 2.04 milligrams in the TSP area, and 1.25 milligrams near CUFL.
The normal phosphate level in water, on the other hand, is considered to be 0.5 milligrams per litre. But phosphate concentrations recorded at the six points were 0.45, 0.22, 2.19, 1.75, 2.25, and 1.40 milligrams per litre, respectively. This means phosphate levels at the last four points were nearly five times higher than the normal standard.
In April, the normal TDS level in water was considered to be around 1,000 milligrams per litre or slightly higher. Although the average TDS level at the first four points was around 300 milligrams per litre, it rose sharply to 13,050 milligrams per litre in the TSP factory area and 16,250 milligrams per litre near the CUFL factory. These levels were many times higher than the normal standard.
Despite still having the levels of pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) in the water within acceptable limits, concerns remain over future environmental risks.
In March, phosphate levels among the six monitoring points ranged from a minimum of 1.16 milligrams per litre in the TSP area to a maximum of 2.87 milligrams per litre in Sikalbaha. The phosphate levels are more than five times higher than the normal standard.
Although ammonium concentrations were comparatively lower at the first three points of the river, levels reached 0.61 milligrams per litre near Kalurghat, 2.41 milligrams in the TSP area, and the highest level of 2.92 milligrams per litre near CUFL.
At the same time, TDS levels were recorded at 19,800 milligrams per litre in the TSP area and 20,800 milligrams per litre near CUFL. However, water quality remained within normal limits under other indicators.
A report published in January 2025 also showed that phosphate levels at different points of the river were several times higher than the normal standard. Among them, the highest phosphate concentration was recorded near Karnaphuli Paper Mills at 4.50 milligrams per litre, while the lowest was found near CUFL at 2.90 milligrams per litre. Ammonium levels reached 8.05 milligrams per litre in the TSP area and 5.46 milligrams per litre near CUFL. TDS levels were also recorded at 18,540 milligrams per litre in the TSP area and 20,100 milligrams per litre near CUFL. This means that during that period, the river’s water quality was polluted several times beyond normal levels.
Officials at the Department of Environment’s laboratory said the Karnaphuli River is connected to the Bay of Bengal. Due to tidal movements, seawater enters the river, resulting in comparatively higher salinity levels. Since the TSP and CUFL fertiliser factory areas are located in the lower part of the Karnaphuli River, pollution indicators and TDS levels there were found to be much higher than normal.
On the other hand, areas near Karnaphuli Paper Mills, Mariumnagar, Sikalbaha, and Kalurghat Bridge are located upstream, where the seawater’s influence is relatively lower. However, massive volumes of sewage flowing through various canals of the city into the lower stretches of the Karnaphuli are severely affecting water quality.
Pollution is also increasing further as various industries along the riverbanks are discharging untreated waste directly into the river without effluent treatment plants (ETPs). Although the levels of pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were still close to acceptable limits, those indicators could also deteriorate in the future if the current situation continues, officials said.
They also noted that the use of large lighterage vessels as floating warehouses in the Karnaphuli River is consequently contributing to pollution through discharged waste oil from ships. They, however, believe that untreated urban sewage remains the primary cause of river pollution at present.
Md Kamrul Hasan, deputy director of the Chattogram Department of Environment laboratory, told Bonik Barta, “Water samples are collected from six points of the Karnaphuli River and tested for quality. The tests found that phosphate and ammonium levels at several points were several times higher than the prescribed standards. At two points, salinity and TDS levels were also found to be abnormally high. In reality, the city’s waste is entering the Karnaphuli River through various canals without any treatment. The direct discharge of sewage into the river is particularly increasing ammonium and phosphate concentrations. Consequently, the water of the Karnaphuli River is gradually becoming unusable.”
Relevant stakeholders said government and autonomous institutions such as Karnaphuli Paper Mills, the City Corporation, WASA, CUFL, and ERL are mainly responsible for pollution in the Karnaphuli River.
On average, between 2,500 and 3,000 tonnes of waste flow into the Karnaphuli River every day through different canals. These wastes include household sewage, chemicals, plastics, heavy metals, and liquid industrial waste. Due to the absence of an effective waste treatment system for a long period, layers of pollutants have accumulated on the riverbed, making the situation increasingly severe.
Aliur Rahman, general secretary of the Chattogram River and Canal Protection Movement, has been campaigning for years to protect Chattogram’s rivers. Speaking to Bonik Barta, he said, “Waste generated by nearly 7 million people in the city is flowing directly into the Karnaphuli River through the city’s canals. Along with human waste, various chemicals are also entering the river, which is severely degrading water quality. Due to this alarming pollution, nearly 70 to 73 species of fish are now at risk of extinction. Chattogram WASA and the Chattogram City Corporation are mainly responsible for this sewage management failure. Although ETPs are mandatory for large industries, untreated waste is still being discharged into the river in many cases because of weak monitoring. As a result, the Department of Environment can’t avoid responsibility either. The growing accumulation of polythene and solid waste in the river has also created navigability problems. Karnaphuli’s water is currently becoming unsuitable for use. City residents must also become more aware of not dumping waste into canals and rivers.”
Human waste, household sewage, and untreated liquid waste from industries are mainly responsible for the excessive presence of ammonium and phosphate in the water, officials of the Department of Environment said.
They explained that higher phosphate concentrations in water lead to abnormal algae growth, or eutrophication, which reduces dissolved oxygen levels and creates severe risks for fish and aquatic life. Similarly, high levels of ammonium negatively affect the respiratory and reproductive systems of aquatic organisms.
In the lower stretches of the Karnaphuli, tidal inflow of saline seawater is also increasing TDS levels. If the situation continues in the long term, the river’s natural biological balance could collapse. At the same time, the river water will gradually become unsuitable for agriculture, fisheries, and household use.