Bangladesh is a riverine country. The economy and the environment depend on the river; even therefore, the pollution cannot be stopped. Almost all the country's rivers are being destroyed due to pollution, just like Chittagong's Karnaphuli is under such severe pollution. Consequently, a global initiative campaign known as the International Day of Action for Rivers seeks to increase public understanding of the significance of preserving and protecting rivers and other waterways. Every year on March 14, this day encourages people and communities to band together and take concrete steps to safeguard these essential resources.

More than three hundred factories are built on both sides of the river, and garbage in the metropolis is one of the causes of pollution; such information has emerged in a report by the Department of Environment. Chaktai Canal and Rajakhali are among the several branches of Karnaphuli. Through these canal, black water flows directly into the river. An average of five thousand tons of industrial, commercial and residential waste of the city is falling into the famous Karnaphuli river of the port every day. Karnaphuli is polluted and shrinking due to various reasons including unplanned urbanization and industrialization. As a result, the river is facing an existential crisis. It is also causing adverse effects on aquatic organisms, public health, social life and economy of the country. These issues are also mentioned in the 10-year master plan for the protection of the Karnaphuli river. The Karnaphuli river with a length of 275 km and an average width of 667 meters is now suffering from excessive encroachment and pollution. Biodiversity is under threat due to pollution. At least 30 species of fish have been lost.

Non-perishable sewage system in Chittagong city and district, non-perishable waste, unplanned hill cutting, industrialization and urbanisation, low landfilling, inadequate waste management, shipbuilding and repair industry, loss of Kaptai Lake's navigability, Karnaphuli Paper Mill, STP (Sewage Treatment Plant) in Naujane. Along rivers and canals, there is a lack of resources, insufficient boats, and transient markets. The city contains around 50,000 sanitary and 24,000 latrine facilities, all of which have direct access to the Karnaphuli river. Due to the lack of sewage infrastructure in the city of Chittagong, Karnaphuli is the last destination for sewage waste from multi-story and commercial buildings, stores, markets, shopping malls, hospitals, diagnostic centres, hotels, and numerous industrial facilities. 36 small and large canals and drains carry these pollutants to the river. On the other hand, incidents involving massive lighter ships have occurred multiple times on the river. A significant quantity of fuel oil is discharged into the lake. Oil accumulation on the river's surface prevents oxygen from interacting with the water. Consequently, there is a deficiency of oxygen in the water. Aside from this, the boats that use the Karnaphuli river frequently dump various rubbish into the river. 443 At the port of Chittagong, cargo is unloaded by lighterage ships. On the other side, 2,000 international ships enter Chittagong port annually via the Karnaphuli river. Every month, an average of 1,500 domestic ships pass through this river. During the cleaning and repair of domestic and foreign ships, metal compounds such as zinc, lead, and cadmium are released into the water and pollute Karnaphuli. In addition, clinker, gypsum, soda, ash, and other materials carried to the port are dispersed in the air and fall into the ocean. The Chittagong Water Supply and Sewerage Authority (WASA) was created in 1963 as a water supply and sewage authority but could not carry out sewerage operations. On both sides of the river Karnaphuli, 700 small and large factories have left their garbage behind. Approximately 62 distinct types of extremely hazardous chemical pollutants from these factories are present in the river water. Every year, three thousand kg of mercury are discharged in Karnaphuli by paper mills and rayon factories. The garbage from the factories enters the Karnaphuli river through eight city sites or canals.

According to the sources of the Department of Environment, 35 species of fish in the Karnaphuli river have disappeared due to pollution. In the past, 66 species of freshwater, 59 species of mixed water and 15 species of marine migratory fish were found in Karnaphuli. Now 20-25 species of fresh water and 10 species of mixed water fish are almost extinct. Extinct fish include Faisya, Kanchki, Rupchanda, Kalichanda, Pangash, Bacha, Vetki, Pasha, Laitta, Ricksha, Madhu, Pabda, Poa, Mahashol etc. Katla, Rui, Mrigel fish have started to decrease. Another 20 species of fish are threatened. Decomposition of aquatic organisms by 'bacteria' requires a lot of oxygen due to mixing of untreated liquid and solid wastes in river water. It reduces DO (dissolved oxygen) levels in cheese. As a result, there is oxygen deficiency in aquatic animals. It is known that the acceptable level of dissolved oxygen (DO) in water is 4 to 6 mg per liter for the survival of fish and other aquatic animals in Karnaphuli. But zero decimal 1 to 4 milligrams of DO was found in the polluted river water. Experts believe that this level is very dangerous for the survival of aquatic animals. The ideal value of Bio-chemical Oxygen Demand (BOD) in river water is 2 to 3 but currently it is 10 to 25 mg per litre. The acceptable level of electrical conductivity of water is 700 to 2800 microsiemens per centimeter. But now there is an average of 3400 micro siemens per centimeter. The ideal value for chemical oxygen demand (COD) of rivers is 200 mg per litre. But here's more. In recent study by Center for Atmospheric Pollution Studies (CAPS) found that the BOD is very high and DO is very low in Buriganga river water also. That's mean it is very unsuitable environment for aquatic habitat.

On the riverbed, a 2 to 7-meter-thick layer of polythene has collected. As a result, Karnaphuli faces a crisis of navigability. Throughout 2002, plastic bags were prohibited in the country. However, no effect is noticed. Consequently, polythene bag industries have sprung up everywhere. This bag is used without restriction. According to a report, Bangladesh is one of the top 10 nations for plastic and polythene consumption. Polythene does not disintegrate even after a century. Currently, it degrades the soil everywhere it is found. As it collects in riverbeds, causing navigational difficulties, it affects soil fertility by decreasing crop yields as it lingers in the soil. Polyethylene has been detected in the guts of fish. Salt has also been discovered to contain plastics. Polythene combustion pollutes the air. Overall, polythene is a highly hazardous chemical. Consequently, polythene usage has been regulated everywhere. Sadly, there is no enforcement of the law in this aspect in our country. To save the port, a large dredging project was initiated to deepen Karnaphuli, but polythene rapidly became an issue. A dense coating of polyethylene ensnares the dredger. China-imported modern dredger equipment was also required to be returned. As a result, the river cannot be excavated at a regular speed. At least thirty waterways in Karnaphuli are affected by polyethene debris. A layer of polyethene ranging in height from 2 to 7 metres has accumulated near the river's bed. As a result of excessive polythene in the riverbed, the capital dredging project must be completed slowly. Production and marketing of polyethylene was banned in 2002 under the Environmental Protection Act. The Act states, 'Manufacture, import and marketing of polythene articles prescribed by the government shall be punishable with imprisonment for a term not exceeding 2 (two) years or with fine not exceeding 2 (two) lakhs or with both and for each subsequent offense with a term not exceeding 2 (two) years. , the offenders shall be punished with imprisonment not exceeding 10 (ten) years or not less than 2 (two) lakh taka, monetary penalty (fine) not exceeding 10 (ten) lakh taka or both. "Selling, displaying for sale, storing, distributing, transporting for commercial purposes or using for commercial purposes is punishable with imprisonment not exceeding 1 (one) year or a fine not exceeding 50 (fifty) thousand taka or both". Although polythene is banned by law, its production, marketing and use does not stop. Billions of polythene bags are thrown away after use every day across the country including the capital Dhaka. A large part of the discarded polythene bags somehow ends up in the river. A thick layer of polythene has accumulated on the riverbed for a long time. The country's nature and environment are steadily approaching a severe catastrophe. Bangladesh is one of the most at-risk nations in the world in terms of environmental catastrophes. Although there are other causes for the environmental catastrophe, an increase in the use of polythene and plastic products is one of them. In this circumstance, the use of polythene should be discontinued and biodegradable alternatives should be implemented. Bags are being crafted from jute fibre. Additionally, the government should prioritise research and manufacturing of inexpensive biodegradable bags.

Shah Amanat Bridge of Chittagong is located on Karnaphuli river. The flow of the Karnaphuli river has narrowed in the estuary area of the Chaktai canal for three kilometers from below the bridge. Shah Amanat Bridge is under threat due to the increase of char on one side of the river and depth on the other side. As a result, there is a risk of the pillars giving way in the future. Bridges are also at risk. 'Karnaphuli River Bed Depth and Occupancy Survey-2022' report published. According to the report, the depth between pillars 1 and 2 on the north side of Shah Amanat Bridge is supposed to be 25 feet as per the measurement of Firingibazar area, the current depth there is only 7.7 feet. Between pillars 2 and 3, char has risen, fishermen have been seen fishing in the char. The normal depth in the area of pillars 3 and 4 of the bridge is supposed to be 38 feet, the current depth there is 64.7 feet. The normal depth of the river in the area of pillars 4 and 5 is supposed to be 28 feet, but the depth near pillar 4 is 78.6 feet. Due to this depth, Shah Amanat Bridge may be damaged during heavy rains. The guide wall on the southern side of the bridge may collapse.

The Karnaphuli river has shrunk as a result of illegal encroachment. The Chaktai canal that passes across Chakbazar, Ghatfarhadbeg, previously the commercial hub, is now a canal. Not the vessel; there is always trash floating here. Rivers and surrounding canals have become increasingly polluted. The illegal expansion over the river could not be eliminated fully despite the High Court's prohibition. Karphuli river should be protected against unauthorised development, encroachment and pollution. The administration should be proactive to prevent the dumping of industrial garbage in rivers. Thousands of people rely on this river for their livelihoods, agricultural, and water requirements. The port of Chittagong is the centre of the nation's economy. The Karnaphuli River is the port of Chittagong's lifeline. The port will survive if the Karnaphuli river remains. If the port survives, the nation will also live, and the nation's economy will be robust. The national economy will increase in value. The development of the nation will accelerate. If the economy is thriving, the nation's total progress will be realised.

Professor Dr. Ahmad Kamruzzaman Majumder, Dean, Faculty of Science, Chairman, Department of Environmental Science, Stamford University Bangladesh, Joint Secretary, Bangladesh Poribesh Andolon (BAPA), Founder and Chariman, Center for Atmospheric Pollution Studies (CAPS). E-mail: kamrul_sub@hotmail.com, dk@stamforduniversity.edu.bd