Assam is one state in India which experiences incessant water scarcity despite having a large number of water resources like the river Brahmaputra River along with the tributaries, various ponds, lakes, underground water, heavy rainfall etc.
The Guwahati metropolitan area is no different although the Brahmaputra flows right on its periphery. The Bharalu River was also once an important source of water supply, now having turned into nothing worse than a drain.
Apart from the rivers, Guwahati also has its fair share of other major water bodies which include the Deepor Beel, Dighali Pukhuri, Jorpukhuri, Silsako Beel, Soru Sola Beel, Bor Sola Beel and Soubhagya Pond amongst others. Yet the city continues to complain about insufficient drinking water.
Citizens and experts have often complained about the gradual conversion of most of these water bodies into dumping grounds. To take stock of the pollution level of the Brahmaputra and its tributary, the ‘dying’ Bharalu River, G Plus approached the Pollution Control Board of Assam (PCBA).
The data of the various parameters for Water Quality Index (WQI) provided by the pollution board shows that the quality of water in the major water sources of the city are ‘Unsatisfactory’.
Parameters of Checking WQI under the National Water Monitoring Programme
As per the pollution control board website, the Water Quality Index (WQI) is a single defining criterion, either 'Satisfactory' or 'Unsatisfactory'. There are four main parameters calculated to determine this index which include:
1. Dissolved Oxygen (DO): The measure of how much oxygen is dissolved in the water. It should be more than 4 milligram per litre (>4.0mg/l)
2. Biological Oxygen Demand (BOD): The measure of the amount of oxygen required to remove waste organic matter from water. It should be 3 milligram per litre (<3.0mg/l).
3. Fecal Coliform: The presence of fecal coliform bacteria in aquatic environments indicates that the water has been contaminated with the fecal material of man or other animals. It should be limited to less than 2500 MPN (most probable number) per 100 litres of water (<2500 MPN/ 100 ml).
4. Total Coliform: The total coliform bacteria test is a primary indicator of "potability,” suitability for consumption of drinking water. It measures the concentration of total coliform bacteria associated with the possible presence of disease causing organisms. It should be limited to less than 5000 MPN (most probable number) per 100 litres of water (<5000 MPN/ 100 ml).
The pollution board clearly states that even one single parameter from these four parameters exceeding the criteria value renders any water to be considered as 'Unsatisfactory'.
Water Quality Index of Brahmaputra and Bharalu
Here’s the WQI of the Brahmaputra River at different locations of Guwahati and the Bharalu River from January 2020 to October 2020, based on monthly/quarterly monitoring data, as provided by the PCBA during the period.
The parameter readings of the Brahmaputra are below the ideal satisfactory mark, but the pollutant level of the Bharalu is much higher. 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. The Bharalu River was even categorized under the 'priority 1' category of polluted river stretches by the CPCB.
Although the pollutants level have diminished in the last year, with BOD of the river being reduced from 52 mg per litre to 38.6 mg per litre, the WQI of Bharalu continues to be labeled as ‘Unsatisfactory’ by the Pollution Control Board of Assam.
Reasons behinds the high level of water pollution
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. Environment scientists are of the opinion that as the city’s untreated sewage waste goes directly into the river in the absence of a sewage treatment plant, the pollution levels in Bharalu River has not gone down over the years. Also Guwahati is yet to adopt the habit of segregating its daily waste.
Authorities have been demanding the setting up of a sewage treatment plant (STP) in the city for a long time. Sources have also mentioned that the Pollution Control Board has been repeatedly writing to the Guwahati Municipal Corporation (GMC) as well as to the Guwahati Development Department, demanding the setting up of an STP but the same has gone unheard till date.
Manojit Bujarbarua, Executive Engineer of GMC, who is in charge of the city’s waste management, informed that the government is yet to provide for the much needed treatment plant. “The municipal corporation does not have any plan to set up an STP in the near future as of now,” he said.
The untreated waste also falls into the Brahmaputra River- the lifeline of Assam and pollutes it. Environmentalists feel that if steps are not taken, the Brahmaputra River will also become highly polluted in the future.
Apart from the two rivers, as per data provided by PCBA, a few other major water sources of the city are also on the verge of dying. These include the Bor Sola Beel at Sarabbhatti and Soru Sola Beel at Paltanbazar (with complete absence of dissolved oxygen- NIL), and Silsako Beel, Chachal.
