In an alarming development, 44 rivers in the state have been listed as the most polluted rivers in India. This was recently revealed by Minister for Environment, Forest & Climate Change, Prakash Javadekar, in a question-answer session of the Lok Sabha.
The revelation was based on data provided by the Central and State Pollution Control Boards.
The data also revealed that 16 rivers in Assam were listed in the most polluted rivers in the country list in the last one and a half years.
The rate of pollution of the rivers and water bodies of Assam has also been increasing at a very high rate. Currently there are 351 polluted rivers in India.
Some of the most polluted rivers from Assam in the list include Bharalu, Brahmaputra, Bhogdoi, Beki, Jiyabhoroli, Kalang, Kapili, Janji, Puthimari and Ronganadi among others.
It should be mentioned that the central government is currently preparing a scheme to protect and cleanse the rivers, excluding Ganges and its tributaries, under Water (Prevention & Control of Pollution) Act of 1974.
However, Brahmaputra river has not been included in this scheme.
Bharalu maintains poor water quality index
Further, as per the latest data collected by the Pollution Control Board of Assam (PCBA), Bharalu River fares badly on all parameters which are used to measure water quality index and the level of pollution in water.
According to data on water quality collected by the state pollution control board in January this year, Bharalu River’s biological oxygen demand (BOD) remained much higher than the prescribed level. The BOD measures the quality of river water, especially the population of coliform bacteria or disease-causing bacteria. As per the Central Pollution Control Board (CPCB), a water body with BOD of more than 3 milligram per litre is considered to be polluted.
However, Bharalu’s BOD for January was 18, which further increased to 38 in February.
Further, the river has also recorded presence of coliform bacteria at a large scale. While the limit of total coliform is less than 5000 most probable number (mpn) per 100 ml, Bharalu River recorded total coliform of a whopping 21,000 mpn per 100 ml in January. Additionally, this figure remained constant in February 2019.
This suggests presence of high level of contamination and disease-causing pathogens ion the water.
Similarly, the river also showed presence of large amounts of faecal coliform which is the presence of bacteria and other pathogens in faeces. The maximum permissible limit for faecal coliform is 2500 mpn per 100 ml. But the PCBA data showed faecal coliform of 21,000 in January in Bharalu river. However, it dropped to 15,000 in February.
The CPCB had conducted a study across India in 2008 and declared Bharalu as among the 71 most polluted rivers in India. Experts say that since then, although the government has taken some measures to reduce the levels of pollution, a lot still needs to be done to improve the quality of river, its aquatic life and its surrounding ecosystem.
Brahmaputra’s water quality satisfactory
On the other hand, the data revealed that water quality index of Brahmaputra river was found to be satisfactory by the authorities.
According to data, in the month of January, the river’s BOD level was 1.9 which is within range. As per the Central Pollution Control Board (CPCB), a water body with BOD of more than 3 milligram per litre is considered to be polluted. Maintaining levels of BOD in a water body also helps in keeping the aquatic organisms healthy. Further, the BOD of Brahmaputra remined at 1.9 in February as well.
Additionally, the river recorded total coliform of 2100 and faecal coliform of 730 in January. However, the levels of both total as well as faecal coliforms increased in February as compared to the previous month. Total coliform as recorded in February was 3600 while faecal coliform was 1500.
River pollution inching towards disastrous levels if steps not taken
Experts maintain that river pollution in the state could reach disastrous levels if steps are not taken to improve the water quality index.
“One of the major reasons that the pollution levels in Bharalu River has not gone down over the years is because the city’s untreated sewage waste goes directly into the river in the absence of a sewage treatment plant in the city,” informed senior environmental scientist at PCBA, Mridul Adhikary.
He added, “We have written to the Guwahati Municipal Corporation (GMC) as well, as to the Guwahati Development Department of the state government from time to time asking them to set up a STP to treat city’s waste before it goes into the rivers.”
Experts working in the field of environment say that since Guwahati has been selected to be developed as a “smart city,” the authorities must be concerned about the proper treatment and disposal of city’s waste.
The untreated waste also falls into the Brahmaputra River - the lifeline of Assam and pollutes it, too. Environmentalists feel that if steps are not taken, the Brahmaputra River will also become highly polluted in the future.
“Large comprehensive planning and an overall management of the polluted rivers from upstream to downstream is needed,” said a city-based environmentalist.