Faecal truth: E-coli thriving in Mahim creek, big threat to fish
Water quality in the Mahim creek is ‘bad to very bad’, making it unsuitable for the survival of any aquatic life, says a study by the Indian Council of Agricultural Research (ICAR) - Central Institute of Fisheries Education (CIFE), Mumbai, which was published in the Indian Journal of Ecology recently.
The study, by researchers Pravin Sapkale, Neelam Saharan, Sanath Kumar, Vidya Bharati, and Kundan Kumar found that faecal coliform (FC) — an indication of human and animal excreta — in the creek is 180 times the safe limit prescribed by the Central Pollution Control Board (CPCB). Untreated domestic sewage flowing into the creek through the Mithi river has caused the FC count — measured as colonies of coliform per 100 millilitre (ml) of water — to be as high as 18,000/100ml against safe standards of 100/100ml.
“We found the presence of drug-resistant bacteria known as Escherichia-coli, or E-coli — a microorganism widely found in the intestinal tract of humans — thriving in the creek water,” said one of the authors of the study.
“The lowest range of FC was 4,200/100ml, which is extremely dangerous as millions of litres of sewage continue to get released in the coastal water. Pollution levels are highest during the pre-monsoon period.”
Researchers studied the water quality from December 2016 to December 2018 by collecting samples from three stations along Mahim creek and Mithi river — Mahim-Bandra pipeline, Bandra-Sion Link Road and Bandra Kurla Complex.
Mahim creek covers the last 1.3-km stretch of the 17.8-km Mithi river before it discharges into the Arabian Sea. The study identified that much of the untreated domestic waste entering the Mahim Bay area was being discharged from nearby slums. On the other hand, industries along the Dharavi belt were responsible for the chemical effluents being released into the water.
“The level of contamination is very high and human impact is responsible. A variety of hazardous pathogenic bacteria, virus, and protozoa are present, and it can lead to diseases. Human health is at risk since these bacteria contaminate sea food, which is ultimately consumed by humans,” said another co-author of the study.
As per the study’s suggestions, illegal encroachment, reclamation, construction, and dumping along the creek need to be stopped and mangrove plantation increased to restore the ecosystem of the area. However, coastal regulation zone (CRZ) rules, 2018, have allowed further reclamation along the creek belt.
“Redevelopment activities have been planned along the Mahim Bay, and the civic body has already been informed to increase efforts to clean the creek. The matter is being monitored by a Supreme Court committee,” said an official from the state environment department.
YB Sontakke, joint director (water quality), Maharashtra Pollution Control Board (MPCB) did not comment on the study but said he will direct officials to inspect the area and check water quality.
Brihanmumbai Municipal Corporation (BMC) said desilting activities were underway and efforts are being taken to curb pollution of the creek. “₹10 crore has been invested for desilting activities, which will be completed by May-end. The sewage operations department has planned treatment plants at the site and solid waste management teams are collecting and treating waste at source. Encroachment removal will be expedited post monsoon,” said Vijay Khabale, public relations officer, BMC.
While mangrove planting will have a positive impact on the area, the state mangrove cell pointed out that it will not help improve water quality, as suggested by the study. “High FC content does not come as a surprise as only slums surround the creek, discharging sewage. There is no space for mangrove trees along the river or creek bed. The only solution is improved treatment at source,” said N Vasudevan, additional principal chief conservator of forest, state mangrove cell.