GUWAHATI: A decade ago, the Central Pollution Control Board (CPCB) declared the Bharalu river as one of the most polluted rivers in the country, however, its levels of pollution remain dismal even after 10 years.
Data obtained by the Pollution Control Board of Assam (PCBA) for three recent consecutive months shows that the river fares badly on all parameters which are used to measure water quality index and the level of pollution in water.
Biological Oxygen Demand
As per the data, the biological oxygen demand (BOD) of Bharalu 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 CPCB, a water body with BOD of more than 6 milligram per litre is considered to be polluted.
However, while Bharalu’s BOD levels decreased over the course of three months, it still remained much above the prescribed limit. In August last year, the river recorded a BOD of 26, while in September this figure was 14 and it decreased to 9.3 in October.
Coliform Bacteria
Further, the Bharalu 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 2,40,000 mpn per 100 ml in August. Additionally, this figure was 2,40,000 in September and 1,10,000 in October.
This suggests presence of high level of contamination and disease-causing pathogens ion the water.
Similarly, the river also showed presence of large amount 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 2,40,000 in August in Bharalu river. However, it dropped to 1,10,000 in September and further declined to 46,000 in October.
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.
Absence of sewage treatment plant a major hurdle
Experts say that the primary reason for Bharalu’s toxicity is the untreated sewage waste from the city which goes directly into the river – making it highly toxic.
The demand for setting up a sewage treatment plant (STP) in the city has been ongoing for a long time now. However, the authorities have turned a blind eye as no steps have been taken by them in this regard.
“One of the major reasons that the pollution levels in Bharalu river has not gone down over the years is because of 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.
An official at the GMC informed G Plus that the municipal corporation does not have any plan to set up a STP in the near future as of now.
“We are lucky that until now, the Brahmaputra has its own self- purification capacity and high current because of which the problem of pollution in Brahmaputra is not as severe. But the water becomes purified after travelling a certain distance and the people living near the source of polluted water who use it for domestic purposes are still at risk,” mentioned Adhikary.
Comprehensive plan needed to save Bharalu: Experts
Environmental experts feel that a comprehensive plan is needed to be developed in order to save the river.
Dr Chandan Mahanta, faculty at civil engineering department at IIT Guwahati said, “Unless there is flow augmentation from the upstream and unless there's no fresh water flow into the river, all it is carrying in the dry season is just sewage waste. One cannot convert a sewage drain into a river.”
He added that there are two sets of problems; one is the problem of flooding during monsoons and the other is extreme water quality problem of low flow during the dry season.
“Large comprehensive planning and overall management of the river from upstream to downstream is needed, only then will it survive as a river,” said Mahanta.
